from ino.it - Istituto Nazionale di Ottica

Programme 12 november 2015 8:30 Registration 9:00 Welcome (Corrado Spinella, Paolo De Natale, Maurizio De Rosa) 9:30 Invited Talk Ady Arie, Tel Aviv University (Israel) Adiabatic frequency conversion Session 1 (Francesco Minardi) 10:20 Silvia Viciani, INO Firenze Experimental observation of noise assisted transport in an all-­‐optical cavity-­‐based network 10:40 Andreas Trenkwalder, INO Sesto Fiorentino: Bose-­‐Einstein-­‐Condensate with tunable interactions in a double well potential 11:00 Coffee Break 11:20 Daniele Cozzolino OSA Chapter Naples 11.40 Round Table: Advanced optical diagnostics Optical technologies are increasingly playing a vital role in developing new sensors and diagnostic tools for a growing number of applications. This round table will gather renowned experts to discuss the most recent achievements in the field of optical sensors, photonic materials, and optical diagnostic tools, in view of present and future applications. Riccardo Chirone (CNR, Istituto di Ricerche sulla Combustione) Antonello Cutolo (Università degli Studi del Sannio) Antonio Varriale (CNR, Istituto di Scienze dell'Alimentazione) Gianluca Gagliardi (CNR, Istituto Nazionale di Ottica) Maurizio Peruzzini (CNR, Istituto di Chimica dei Composti Organometallici) Gaetano Scamarcio (Università degli Studi di Bari) Miriam Serena Vitiello (CNR, Istituto Nanoscienze) 13:10 Lunch 13:50 Poster Session Session 2 (Iolanda Ricciardi) 14:40 Simone Borri, INO Sesto Fiorentino Microcavity-­‐stabilized quantum cascade lasers for high-­‐sensitivity and precision spectroscopy 15:00 Pietro Malara, INO Napoli Coupled-­‐resonator based sensors: beyond the traditional cavity enhancement 15:20 Dario Zappa, INO Brescia Low power metal oxide nanowire gas sensors 15:40 Coffee Break Session 3 (Franco Dalfovo) 16:00 Luigi Santamaria, INO Napoli
Low-­‐temperature spectroscopy of the 12C2H2 (υ1 + υ3) band in a helium buffer gas 16:20 Luigi Consolino, INO Sesto Fiorentino
Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser 16:40 Francesco D'Amato, INO Firenze
Laser analyzers for the detection of dangerous molecular species in the atmosphere 17:00 Visit to INO Lab, Pozzuoli 20:00 Pizza Dinner 13 november 2015 9:00 Welcome speech by the Mayor of Naples, Luigi de Magistris 9:10 Invited Talk Philippe Bouyer, LP2N IOA, Bordeaux Large scale atom interferometers for gravitation experiments Session 4 (Camilla Baratto) Camilla Parmeggiani, INO Sesto Fiorentino Liquid crystalline elastomers as artificial muscles towards nanorobotic devices 10:20 Ludovico Silvestri, INO Sesto Fiorentino Optical mapping of neuronal activation across the entire brain with single-­‐cell resolution 10:40 Elisabetta Tognoni, INO Pisa Bias modulation for faster scanning ion conductance microscopy of biological samples 11:00 Fabrizio Sgrignuoli, INO Sesto Fiorentino Photonic necklace states in 2d and integrated single quantum emitters 11:20 Coffee Break Session 5 (Pablo Cancio) 11.30 Riccardo Meucci, INO Firenze A new model for complex dynamics in a dc glow discharge tube 11:50 Elisa Sani, INO Firenze Characterization of ceramic high-­‐temperature solar absorbers 12:10 David Jafrancesco, INO Firenze Optical design of a light-­‐emitting diode lamp for a maritime lighthouse 12:30 Franco Dinelli, INO Pisa Ultrasonic force microscopy: mechanical contrast at the nanoscale for structural analysis of ultrathin films 12:50 Maria Parisi, INO Napoli Frequency comb generation in quadratic nonlinear media 13:10 Lunch 13:50 Poster Session Session 6 (Elisabetta Tognoni) 14:40 Davide Mazzotti, INO Sesto Fiorentino Recent developments of the SCAR apparatus for radiocarbon dioxide optical detection 15:00 Guido Toci, INO Sesto Fiorentino Design and characterization of Yb-­‐doped transparent ceramics for high power laser applications: recent advancements at CNR 15:20 Fernando Brandi, INO Pisa Gas targets for laser-­‐plasma acceleration applications 15:40 Coffee Break 16:00 Round Table: From sensor networks to final applications: platforms for data collection, processing, and transmission Optical sensors and fiber optic sensors may represent one of the physical layers of a more complex structure that comprises both a data layer and a network for data communication and services. In this round table, starting from the physical sensor layer, the possibility to create a flexible platform to develop different applications only based on a software management will be discussed. Romeo Bernini (CNR, Istituto per il Rilevamento Elettromagnetico dell'Ambiente) Guido Caldarelli (CNR, Istituto dei Sistemi Complessi) Giacomo Corvisieri (Italtel S.p.A.) Giuseppe De Natale (INGV, Osservatorio Vesuviano) Mario Martinelli (Politecnico di Milano) Maurizio Mirabile (Hpsystem s.r.l.) Alessandra Rossetti (Vitrociset S.p.A.) 17:30 Closing Remarks Invited talks
Adiabatic frequency conversion
A. Arie
School of Electrical Engineering, Fleischman Faculty of Engineering,
Tel Aviv University, Tel Aviv, Israel
Adiabatic processes in a dynamical system occur when an external perturbation of the system
varies very slowly compared to its internal dynamics, allowing the system the time to adapt to the
external changes. These processes were investigated in many subfields in physics, e.g. adiabatic
evolution in nuclear magnetic resonance, coherently excited quantum atomic systems, coupled
waveguide arrays, etc. In recent years it was realized that adiabatic processes can also play a
significant role in optical frequency conversion. Adiabatic frequency conversion enabled to
achieve efficient scalable broadband frequency conversion and was applied successfully to the
conversion of ultrashort pulses, demonstrating near-100% conversion efficiency for broadband
signals. Furthermore, multiple adiabatic processes enabled to achieve complete frequency
conversion through an absorptive intermediate level. Additionally, the undepleted pump
restriction was removed, enabling the exploration of adiabatic processes in the fully nonlinear
dynamics regime of nonlinear optics. The fundamentals of adiabatic optical frequency conversion
as well as the recent developments in this field will be reviewed.
Large scale atom interferometers for gravitation experiments
P. Bouyer1
1
LP2N, IOA, Rue François Mitterrand, F-33400, Talence, France
Atomic Interferometry (AI) has shown to be an extremely performing probe of inertial forces, and has revealed
sensitivities to acceleration or rotation competing with or even beating state-of-the art sensors based on other
technologies. The high stability and accuracy of AI sensors relying on cold atoms is at the basis of several
applications ranging from fundamental physics (e.g. tests of general relativity [1, 2] and measurements of
fundamental constants [3–5]), geophysics (gravimetry [6], gradiometry [7]) and inertial navigation [8]. In
contrast with many experiments, which aim at making AI small and compact [9], large-scale matter-wave sensor
open new applications in geoscience and fundamental physics.
Increasing sensitivity for gravitation experiments relies on
increasing the interferometer baseline, either by increasing the
interferometer area [10] or by performing differential
measurements on a large scale.
Increasing the interferometer area is achieved by extending the
interrogation time [10]. We will review the recent experimental
results with free-fall dual species interferometer [11], where
two atomic species, 39K and 87Rb, are used to veriy that two
39
massive bodies undergo the same gravitational acceleration
K (blue) and 87Rb (red) interference fringes
regardless of their mass or composition. In another experiment,
large scale differential gravitational measurement is using an
array of Atom Interferometers (AIs) configured to differentiate
Newtonian Noise, geodetic signal anf GW detection. In this
gravitation antenna, each of the AIs measures the local gradient of
gravitational acceleration and the correlation between distant
sensors enables to cancel out fluctuations of the terrestrial
gravitational forces. With the foreseen cold atom technology
developments in the next decade, strain sensitivities down to 1019
in the 0.1-10 Hz band are within reach, offering interesting
complementary observations to optical GW detectors operating at
higher frequencies.
[1] S. Dimopoulos, P. W. Graham, J. M. Hogan, and M. A. Kasevich,
The AI Gravitation Antenna prototype.
Phys. Rev. Lett. 98 , 111102 (2007).
[2] D. N. Aguilera, et al. , Class. Quantum Grav. 31 , 115010 (2014).
[3] J. B. Fixler, G. T. Foster, J. M. McGuirk, and M. A. Kasevich, Science 315 , 74 (2007).
[4] G. Lamporesi, A. Bertoldi, L. Cacciapuoti, M. Prevedelli, and G. M. Tino, Phys Rev. Lett. 100, 050801 (2008).
[5] R. Bouchendira, P. Cladé, S. Guellati-Khelifa, F. Nez, and F. Biraben, Phys Rev. Lett. 106 , 080801 (2011).
[6] A. Peters, K. Y. Chung, and S. Chu, Nature 400 , 849 (1999).
[7] M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys Rev. Lett. 81, 971 (1998).
[8] M. A. Kasevich and B. Dubetsky, United States Patent 7317184.
[9] Bongs, Kai, et al., Quantum Information and Measurement. Optical Society of America, 2014.
[10] R. Geiger, et al., Nature comm. 2, 474 (2011).
[11] B. Barrett, et al., Proceedings of the International School of Physics “Enrico Fermi” on Atom Interferometry (2014).
Oral presentations
Experimental Observation of Noise Assisted Transport in an
All-Optical Cavity-Based Network
S.Viciani1,2, M.Lima1,2, M. Bellini1,2, F. Caruso2,3,4
1
CNR-INO, National Institute of Optics, Firenze, Italy
LENS, European Laboratory for Non-linear Spectroscopy, Sesto Fiorentino, Italy
3
Dipartimento di Fisica e Astronomia, Università di Firenze, Sesto Fiorentino, Italy
4
QSTAR, Firenze, Italy
2
The transmission of energy through interacting systems plays a crucial role in many
fields of physics, chemistry, and biology. Recently a large theoretical and experimental
work has been undertaken to explain the high efficiency of the excitation transfer
through a network of chromophores in photosynthetic systems, or, more in general, to
study the process of transferring energy and information across complex networks.
Theoretical models have predicted that noise can play a positive role in assisting energy
transport (“Noise Assisted Transport”) and a maximum value of the transport efficiency
is expected in correspondence of a particular amount of noise due to dephasing
mechanisms.
We have realized an optical simulator of complex networks, that mimics a network of
chromophores in photosynthetic systems, where the coherent propagation of excitons in
a N-sites (or N-chromophores) network is simulated by the propagation of photons in a
network of N coupled optical cavities. The setup is entirely based on fiber optic
components and the optical cavities, that play the role of chromophores, are realized
with Fiber Bragg Grating (FBG) Resonators. The simulator is simple and scalable, with
several controllable parameters and variable topology, and with the possibility of
introducing a measurable amount of noise.
This setup has led to the first experimental observation of the bell-like shape of the
network transport efficiency as a function of dephasing noise [1]. Moreover a complete
investigation of the dependence of the transport efficiency as a function of both the
network characteristics and the noise features has been carried out.
This work points towards the possibility of designing optimized structures for transport
assisted by noise that might also be used for future and more efficient solar energy
technologies.
References
[1] S.Viciani, M. Lima, M. Bellini, F. Caruso, Observation of Noise-Assisted Transport in an All-Optical
Cavity-Based Network, Physical Review Letters, 115 (2015) 083601 1-5.
Presenting author: Silvia Viciani, CNR-INO, c/o Area CNR, Via Madonna del Piano 10, 50019 Sesto
F.no (FI), phone 0555226332, fax 0552337755, [email protected].
BEC with tunable interactions in a double well potential
A. Trenkwalder1, G. Spagnolli2,3, G. Semeghini2,3, S. Coop2,3, M. Landini1, P. Castilho1,
L. Pezzè1,2,4, G. Modugno2,3, M. Inguscio2,3,5, A. Smerzi1,2,4, M. Fattori1,2,3
1
Istituto Narionale di Ottica- CNR, 50019 Sesto Fiorentino, Italy
LENS European Institute for Nonlinear Spectroscopy, 50019 Sesto Fiorentino, Italy
3
Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino,
Italy
4
Quantum Science and Technology in Arcetry, QSTAR, 50125 Firenze, Italy
5
Istituto Nationale di Ricerca Metrologica, INRIM, 10135 Torino, Italy
2
In this experiment we have created a Bose-Einstein condensate of Potassium 39 atoms in
a double well potential. We control the tunneling rate of the atoms between the wells with
high precision and we tune the interaction strength around zero. At a specific attractive
interaction strength we observe a quantum phase transition between a balanced phase to an
imbalanced phase with a broken parity symmetry. We have characterized this phase
transition at which strong entanglement is expected to appear which will allow us to
measure small forces in an atom interferometer with sub-shot noise precision.
Microcavity-stabilized Quantum Cascade Lasers for high-sensitivity
and precision spectroscopy
S. Borri1, M. Siciliani de Cumis1, G. Insero1, I. Galli1, S. Bartalini1, P. Cancio1, D.
Mazzotti1, G. Giusfredi1, F. Cappelli1, G. Santambrogio2, A. Savchenkov3, D. Eliyahu3,
V. Ilchenko3, N. Akikusa4, A. Matsko3, L. Maleki3, and P. De Natale1
1
CNR-INO - Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI, Italy
and LENS, Via Carrara 1, 50019 Sesto Fiorentino, FI, Italy;
2
INRIM, Strada delle Cacce, 91 - 10135 Torino, ITALY;
3
OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA 91107, U.S.A.;
4
Development Bureau Laser Device R&D Group, Hamamatsu Photonics KK, Shizuoka
434-8601, Japan
The quest for tunable and spectrally pure laser sources in the mid infrared (mid IR) is
one of the most challenging photonic endeavours of the last decades. High-sensitivity
spectroscopic techniques based on high-finesse optical resonators have proved to greatly
benefit from narrow-linewidth lasers, achieving record sensitivity values for trace gas
sensing [1]. Highly-integrated, compact and frequency-stabilized laser sources having
mid-IR emission wavelengths are needed to replace conventional bulky spectroscopy
designs for fieldable mid-IR spectrum analyzers. To this purpose, direct lock of QCLs to
mid-IR cavities stands out as the most attractive solution.
We demonstrate QCLs frequency stabilization and linewidth narrowing by locking to
high-Q mid-IR Whispering Gallery Mode microResonators (WGMRs) [2]. This method
has multiple salient advantages in mid IR. Microcavities, like those used in this work,
are compact and highly versatile, lending themselves for monolithic integration and
development of on-chip IR and mid-IR spectrometers. Moreover, differently from
standard Fabry-Perot cavities, whose highly reflective mirrors operate at very specific
wavelengths, our resonators work over a wide spectral range, from well below 1 m to
above 5 m wavelength, and can be used for stabilization of very different lasers.
We implemented two complementary methods for QCL stabilization, using
self-injection locking as well as all-electronic locking onto the transmission mode. We
achieved 15 kHz linewidth (FWHM) over a 1 s timescale, an unprecedent result for
direct lock to a mid-IR optical resonator [3]. This result paves the way for the
realization of very compact and spectrally pure mid-IR spectrometers suitable for
high-resolution molecular sensing. It is worth noting that the achieved long-term
stability is particularly attractive for demanding spectroscopic measurements, as it
allows for effective averaging over time without loosing in spectral resolution.
References
[1] I. Galli, S. Bartalini, S. Borri, P. Cancio, D. Mazzotti, P. De Natale, and G. Giusfredi, Molecular Gas
Sensing Below Parts Per Trillion: Radiocarbon-Dioxide Optical Detection, Phys. Rev. Lett., 107 (2011),
270802.
[2] A. B. Matsko and V. S. Ilchenko, Optical resonators with whispering gallery modes I:Basics, IEEE J.
Sel. Top. Quantum Electron., 12 (2006), 3-14.
[3] M. Siciliani de Cumis, S. Borri, G. Insero, I. Galli, A. Savchenkov, D. Eliyahu, V. Ilchenko, N.
Akikusa, A. Matsko, L. Maleki, and P. De Natale, Microcavity-Stabilized Quantum Cascade Laser, Laser
Photon. Rev. (accepted, 2015).
Presenting author: Simone Borri, via G. Sansone 1, 50019 Sesto Fiorentino (FI), Italy;
phone: +39 055 4572227, email: [email protected]
Coupled-mode resonators: beyond the standard cavity enhancement.
P. Malara1, C. E. Campanella2, A. Giorgini1, S. Avino1, P. De Natale3 and G. Gagliardi1
1
2
3
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), via Campi
Flegrei, 34, Comprensorio A. Olivetti, 80078 Pozzuoli, Napoli, Italy.
Light-Matter Interactions Unit, OIST Graduate University, 1919-1 Tancha, Onna-son,
Okinawa 904-0495 Japan.
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), Largo E. Fermi,
6, 50125 Firenze, Italy
Optical resonators are a universal tool to extend the interaction length between matter and
field, to build up the optical power or to impose a well-defined mode structure on the
electromagnetic field. In traditional passive devices, i.e. with no gain, these features
depend uniquely on the capability of the resonator to store photons, which is commonly
expressed in terms of a finesse or quality-factor parameter. For this reason the last 30
years have been characterized by a persisting technological effort to realize resonators
with the highest possible quality factors, first by designing ultra-reflective mirror
coatings, and, more recently, by developing high-Q microrings and whispering-gallery
mode resonators with the most diverse geometries and materials.
In this work we demonstrate that the intracavity radiation-matter interaction
length can be manipulated beyond the constraints of traditional standing-wave or
travelling-wave devices in a coupled-mode resonator scheme. The configuration
considered in this work consists of a Fabry Perot resonator (FP) whose output is coupled
back at the input mirror. The supermodes supported by such a resonator consist of two
separated peaks that exhibit an asymmetric transmission behavior in the vicinity of the FP
resonances. In the presence of small FP losses, one peak is transmitted almost
unperturbed, while the other is strongly attenuated. Beyond a critical value, the latter’s
peak trend inverts and its transmission is increased by the intracavity losses.
From the expressions for the effective intracavity pathlengths of the two peaks it
is clear that the supermodes of a self-coupled Fabry-Perot are formed by a
“quasi-transparent” peak, that can have an effective pathlength even shorter than the
single-pass interaction length, and by an “ultrasensitive” peak whose effective pathlength
can exceed the limits imposed by the finesse of the Fabry-Perot cavity or even be
negative.
Low Power Metal Oxide Nanowire Gas Sensors
1
D. Zappa , E. Comini2, M. Herold3, N. Poli2, V. Sberveglieri1 and G. Sberveglieri1,2
1
CNR-INO, UOS Brescia, Brescia, Italy
2
Dept. of Information Engineering (DII), University of Brescia, Brescia, Italy
3
ams Sensor Solutions Germany GmbH, Reutlingen, Germany
Abstract
Metal oxides materials show properties covering almost all aspects of material
science and physics in areas including electronics, superconductivity, ferroelectricity,
magnetism. Among those, metal oxides are already established in the field of gas
sensing. The most common sensing mechanism consists in an electrical resistance
variation upon gas chemisorption. The advantages of using single crystal nanowire of
metal oxides compare to films are: a very large surface-to-volume ratio, the downsizing
of sensing materials that improves the sensor performances, their stability (high degree
of crystalline order), the higher capability to accommodate strain in presence of lattice
mismatch, while the main challenges remains the integration in macroscopic devices
with good and stable electrical contacts [1][2].
As widely known, metal oxide sensing mechanism is thermally activated, and the
optimal working temperature is in the range of 200-400°C [3]. Power consumption of
the whole device is thus a limiting factor for their use in a wide range of applications.
Micro hotplates integrate both electrodes and heating elements on a micro-fabricated
(MEMS) membrane. In particular, ams (http://ams.com/eng) is a leading company in the
field of gas sensor devices, and its family of micro hotplates provided very low power
consumption together with the ability to sustain high working temperature.
Metal oxide nanowires were synthetized on ams substrates in order to fabricate
working gas sensing devices, combining the advantages of nanowire technology with
low-power micro hotplates. Sensors were structurally and morphologically
characterized, and the sensing performance were evaluated in laboratory testing.
These devices proved to have a stable baseline over long time operation, and they are
ideal candidate to be integrated in portable devices like low-power electronic noses for
example.
Acknowledgements
The work has been supported by the Italian MIUR through the FIRB Project RBAP115AYN “Oxides at
the nanoscale: multifunctionality and applications”, and by National Research Council (CNR) and
Lombardia Region through the project “Nuovi approcci e metodologie per un biorisanamento efficace e
sostenibile di acque sotterranee contaminate da idrocarburi clorurati (SUSBIOREM)”.
This work was partially supported by the European Community’s 7th Framework Programme, under the
grant agreement n° 611887 “MSP: Multi Sensor Platform for Smart Building Management”.
References
[1] Wang, X.S., Miura, N. and Yamazoe, N., Sens. Actuator B-Chem. 2000, 66(1-3), 74
[2] Meng, D., Shaalan, N.M., Yamazaki, T. and Kikuta, T., Sens. Actuator B-Chem. 2012, 169, 113
[3] Zappa D., Bertuna A., Comini E., Molinari M., Poli N., Sberveglieri G., Anal. Methods, 2015, 7,
2203–2209
Presenting author: Dario Zappa, Via Valotti 9, 25123 Brescia, +39 030 3715767, [email protected]
Low-temperature spectroscopy of the (υ1+υ3) acetylene band
L. Santamaria1, V. Di Sarno1, I. Ricciardi1, M. De Rosa1, S. Mosca1, G. Santambrogio2,3, P.
Maddaloni1,4, P. De Natale4,5
1
CNR-INO, Istituto Nazionale di Ottica, Pozzuoli, Italy
CNR-INO, Istituto Nazionale di Ottica, Sesto Fiorentino, Italy
3
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
4
INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, Sesto Fiorentino, Italy
5
CNR-INO, Istituto Nazionale di Ottica, Firenze, Italy
2
Laser absorption spectroscopy of v1+v3 band on acetylene is performed at low temperature. The gas
is cooled to about 15 K through buffer gas cooling technique1 using cold helium as buffer gas.
Doppler thermometry is first performed to measure translational molecular temperatures from the
recorded spectra. Then, rotational temperatures down to 20 K are retrieved by fitting the Boltzmann
distribution to the relative intensities of several ro-vibrational lines. Using this setup is possible to
tune the thermal equilibrium between translational and rotational degrees of freedom by changing
experimental parameters (cell dimension and gas pressure). This can be used to reproduce in a
controlled way the regime of non-local thermal equilibrium typically encountered in the interstellar
medium. The low temperature helium-acetylene scattering, relevant for modeling planetary
atmospheres, is also addressed. In particular, the acetylene diffusion time in the buffer gas cell is
measured against the He flux at two different temperatures; the observed behavior is then compared
with that predicted by a Monte Carlo simulation to obtain an estimation for the elastic cross
sections: σ(100 K) = (4 ± 1) × 10–20 m2 and σ(25 K) = (7 ± 2) × 10–20 m2.
References
[1] N. R. Hutzler, H. –I. Lu, and J. M. Doyle, The buffer gas beam: an intense, cold, and slow source
for atoms and molecules, Chemical Reviews, 112 (2012) 4803.
Presenting author: Luigi, Santamaria Amato, INO- CNR via Campi Flegrei n.34, Pozzuoli (NA), 0818675414,
luigi.santamariano.it
Saturated absorption in a rotational molecular transition at 2.5 THz
using a quantum cascade laser
L. Consolino1, M. Siciliani de Cumis1, A. Campa1, M. De Regis1, S. Bartalini1,
M. Ravaro1, D. Mazzotti1, P. Cancio Pastor1, M.S. Vitiello2, P. De Natale1
1
CNR-INO, Istituto Nazionale di Ottica and LENS, Sesto Fiorentino (FI) - Italy
2
NEST-CNR, Istituto Nanoscienze and Scuola Normale Superiore, Pisa - Italy
Abstract
In the terahertz (THz) domain, linestrengths of molecular transitions are generally
larger than in the microwave region and are comparable with the strongest fundamental
ro-vibrational transitions of the mid-IR fingerprint region. High precision THz
molecular spectroscopy therefore promises amazing scientific and technological
applications, provided that sources with suitable high power, wide tunability and narrow
linewidth, such THz Quantum Cascade Lasers [1] are available. In this context, the first
application of a QCL phase-locked to a free-standing THz Frequency Comb Synthesizer
(FCS) [2] was recently demonstrated, achieving a state of-the-art accuracy of 4×10 −9 in
the determination of the absolute frequency of a THz transition [3].
In this experimental report the overall accuracy was limited by the resolution of the
Doppler-broadened direct-absorption spectroscopy adopted therein. As a consequence,
in order to improve the spectrometer, the the development of high-resolution THz
spectroscopic techniques is a mandatory condition for further accuracy improvements.
In analogy with already well-explored spectral regions, saturated-absorption
spectroscopy (SAS), and the possibility to use well-established spectroscopic tools, such
as cavity resonators, are the natural evolution of experimental set-ups aiming to
overcome the limitation set by the Doppler broadening of molecular lines at room
temperature, paving the way to next generation THz metrological tools.
We report on the evidence of saturation effects in a rotational transition of CH 3OH
around 2.55 THz, induced by a free-running continuous-wave QCL [4], confirming the
feasibility of QCL-based subDoppler spectroscopy, once provided that the QCL
emission linewidth is comparable with, or narrower than the Lamb-dip width. The QCL
emission is used for direct-absorption spectroscopy experiments, allowing to study the
dependence of the absorption coefficient on gas pressure and laser intensity. A saturation
intensity of 25 μW/mm2, for a gas pressure of 17 μbar, is measured.
In order to further increase the sensitivity of a spectroscopic system, high-finesse
cavity resonators represent an attractive tool as they give access to much longer
interaction lengths between light and absorbing medium, and could also provide a
narrow reference for a QCL, allowing a reduction of its free-running linewidth. We
report on three different resonant cavities designs, injected by a continuous-wave
quantum cascade laser emitting at 2.55 THz [5].
References
[1] M. S. Vitiello et all, Nat. Photon., 6, 525–528 (2012).
[2] L. Consolino et all, Nat. Commun., 3, 1040 (2012).
[3] S. Bartalini et all, Phys. Rev. X, 4, 021006 (2014).
[4] L. Consolino et all, Appl. Phys. Lett., 106, 021108 (2015).
[5] A. Campa et all, Optics Express, 23, 3751-3761 (2015)
Presenting author: Luigi Consolino, via N. Carrara, 1 50019 Sesto F. (FI) – Italy.
Tel: +39 055 457 2227
Fax: +39 055 457 2451
email: [email protected]
Laser Analyzers for the Detection of Dangerous Molecular Species in
the Atmosphere
F. D'Amato1, S. Viciani1, I. Galli2, D. Mazzotti2, M. Siciliani de Cumis2, M. Burton3, A.
Chiarugi4
1
SPHERES Group, CNR-INO, Firenze, Italy
2
UOS Sesto Fiorentino, INO, Sesto Fiorentino (FI), Italy
3
School of Earth, Atmospheric and Environmental Science
University of Manchester, Manchester, Great Britain
4
Sezione di Pisa, INGV, Pisa, Italy
Abstract
Spectroscopic techniques can be easily and profitably applied to the detection of
molecular species in any matter phase. Atmospheric monitoring is a wide field, driven
by environmental, industrial, safety and climatic issues. According to the specific
requirements, different spectroscopic techniques are adopted. In this contribution two
applications will be described, based on two different techinques, aiming to the
detection of Hydrogen Sulphide (H2S) in geothermoelectric plants, and Hydrogen
Fluoride (HF), Hydrogen Chloride (HCl) and CO2 in volcanic emissions.
An analyzer for the detection of H2S has been realized in the frame of the SIMPAS
Project (Innovative Measurement Systems for the Protection of Environment and
Health), based on Cavity Ring-Down and a fiber coupled laser. This analyzer can be
exploited for monitoring the emissions of geothermal plants for the production of
electricity, in particular in the Amiata and Larderello areas. Its detection limit is 150 ppb
in 5' [1].
Two laser analyzers for the detection of the concentrations of CO2, HF and HCl, and of
the isotopic ratio of HCl in volcanic emissions have been developed in the frame of the
ERC Project CO2Volc. The aim of the project is to assess the contribution of volcanic
emissions to the concentration budgets of these molecules, which are either greenhouse
gases or pollutants. Within the CO2Volc project a third analyzer, based on an UV LED,
has been realized, for the detection of SO2. The ratios between HF, HCl, SO2 and CO2,
together with the isotopic ratio of HCl, can lead to the determination of the status of the
magma inside a volcan. In case of permanent monitoring of a volcan, a variation of
these ratios can lead to an early warning of eruption.
The above devices will be described, and the results of test campaigns will be discussed.
References
[1] M. Siciliani de Cumis, S. Viciani, I. Galli, D. Mazzotti, F. Sorci, M. Severi, and F. D'Amato, Note: An
analyzer for field detection of H2S by using Cavity Ring-Down at 1.57 micron, Rev. Sci. Instr., 86 (2015)
056108, DOI: 10.1063/1.4921582
Presenting author: Francesco D'Amato, c/o Area CNR, Via Madonna del Piano 10, 50019 Sesto F.no
(FI), +39-055-5226333, +39-055-2337755, [email protected].
Liquid crystalline elastomers as artificial muscles towards nanorobotic
devices
C. Parmeggiani1,2, H. Zeng2, D. Martella2,3, P. Wasylczyk2,4, D. S. Wiersma2
1
CNR-INO, U.O.S. Sesto F.no, Sesto F.no, Italy
2
European Laboratory for Non-Linear Spectroscopy, Sesto F.no, Italy
3
Dipartimento di Chimica “Ugo Schiff”, University of Florence, Sesto F.no, Italy
4
Institute of Experimental Physics, Faculty of Physics, Warszawa, Poland
Smart polymers are artificial materials that can respond to external stimuli. Among
these, liquid-crystalline elastomers (LCEs) combine the properties of polymeric
elastomers and liquid crystalline orientations, performing dramatic shape change
(20-400%) under light/heat stimuli [1] and allow for realization of remotely controlled
robots. Important challenges lie in the miniaturization of functional structures. Direct
Laser Writing (DLW) has been recently used to fabricate LCE structures with
sub-micron resolution, exhibiting deformation under light excitation [2].
We present here the realization of polymeric microstructures of which both, shape and
molecular alignment, can be controlled locally with nanometer precision. This allows us
to create free-form polymeric elements – rings, woodpiles, etc. - which can support
multiple functionalities, and which cannot be fabricated with existing techniques.[3]
Photoresponsive LCEs can be prepared including photosensitive molecules, such as
azobenzene, inside the chains or dispersed in the polymers. We show experimentally
that under a spatially uniform laser illumination, such structures can deform along
different directions according to the local micro-grating direction. Moreover, the
technique is versatile and consents to combine different materials to create composite
devices. These results lay the foundations for creating 3D, micron-sized,
light-controlled LCE structures fundamental building blocks in micro-robotics such as
the recently presented microscopic walker entirely powered by light [4].
Acknowledgements. The research leading to these results has received funding from
the European Research Council under the European Union's Seventh Framework
Programme (FP7/2007-2013) / ERC grant agreement n° [291349] on photonic micro
robotics
References
[1] M.-H. Li, P. Keller, B. Li, X. Wang, M. Brunet, Light-Driven Side-On Nematic Elastomer Actuators
Adv. Mater. 15 (2003), 569-572.
[2] H. Zeng, D. Martella, P. Wasylczyk, G. Cerretti, J. C. Gomez Lavocat, C.-H. Ho, C. Parmeggiani, D.
S. Wiersma, High Resolution 3D Direct Laser Writing for Liquid Crystalline Elastomer Micro Structures
Adv. Mater. 26 (2014), 2319-2322.
[3] H. Zeng, P. Wasylczyk, G. Cerretti, D. Martella, C. Parmeggiani, D. S. Wiersma, Alignment
engineering in liquid crystalline elastomers: Free-form microstructures with multiple functionalities App.
Phys. Lett. 106 (2015), 111902.
[4] H. Zeng, P. Wasylczyk, C. Parmeggiani, D. Martella, M. Burresi, D. S. Wiersma Light-Fueled
Microscopic Walkers Adv. Mater. 27 (2015), 3883-3887
Presenting author: Camilla Parmeggiani, CNR-INO U.O.S. Sesto Fiorentino, via N. Carrara 1, Sesto
Fiorentino (FI), 0554572505, [email protected]
Optical mapping of neuronal activation across the
entire brain with single cell resolution
L. Silvestri1,2, M. Paciscopi3, N. Rudinskyi4, M. C. Müllenbroich2,5, A. L. Allegra
Mascaro1,2, I. Costantini2, L. Sacconi1,2, P. Frasconi3, B. T. Hyman4, F. S. Pavone2,5,1
1
National Institute of Optics, National Research Council, Sesto Fiorentino, Italy
2
European Laboratory for Non-linear Spectroscopy, Sesto Fiorentino, Italy
3
Department of Information Engineering, University of Florence, Florence, Italy
4
Harvard Medical School, Boston, United States
5
Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
The ability to map neuronal activity patterns in the brain with single-cell resolution is
a crucial technological step to afford a clearer view of brain activity and of its relation
with long-range connectivity architecture. Despite a number of technological efforts,
quantitative cellular-resolution activation maps of the whole brain have not yet been
obtained. In fact, many state-of-the-art techniques are limited by coarse resolution or by
a narrow field of view. Even cutting-edge approaches such as high-speed calcium via
wide-field microscopy are limited to the most superficial layer of the cortex [1].
The general problem is that high resolution imaging of the whole mouse brain is
currently possible only in fixed samples, precluding the possibility of tracing
whole-brain activity in real time and with single-neuron resolution. A compromise to
gather information on neuronal activation over a brain-wide scale is to use genetic
approaches to tag neurons which have been active [2].
Here, we present a full experimental pipeline to quantify neuronal activity in the
entire mouse brain with cellular resolution, based on a combination of genetics, optics
and computer science. We used a transgenic mouse strain (Arc-dVenus mouse) in which
neurons which have been active in the last hours before brain fixation are fluorescently
labelled. Samples were cleared with CLARITY and imaged with a custom-made
confocal light sheet microscope (CLSM, [3]).
With CLSM, it is possible to image entire mouse brains at micron resolution in few
hours, allowing high-throughput analysis of multiple specimens. However, each sample
results in a dataset in the TeraByte range, making manual image analysis an unattainable
task. To perform an automatic localization of fluorescent cells on the large images
produced, we used a novel computational approach called semantic deconvolution [4].
The combined approach presented here allows quantifying the amount of
Arc-expressing neurons throughout the whole mouse brain. When applied to cohorts of
mice subject to different stimuli and/or environmental conditions, this method would
help finding correlations in activity between different neuronal populations.
Furthermore, it can be coupled with in vivo imaging to assess a more comprehensive
and multi-scale view of brain activity.
References
[1] D. A. Vousden et al., “Whole-brain mapping of behaviourally induced neural activation in mice”,
Brain Structure and Function, 220(4), 2043-58 (2015)
[2] M. P. Vanni, T. H. Murphy, “Mesoscale Transcranial Spontaneous Activity Mapping in GCaMP3
Transgenic Mice Reveals Extensive Reciprocal Connections between Areas of Somatomotor Cortex”, J.
Neurosci., 34(48), 15931-46 (2014)
[3] L. Silvestri et al., “Confocal light sheet microscopy: micron-scale neuroanatomy of the entire mouse
brain”, Opt. Exp., 20(18), 20582-98 (2012)
[4] P. Frasconi et al., “Large-scale automated identification of mouse brain cells in confocal light sheet
microscopy images”, Bioinformatics, 30(17), i587-i593 (2014)
Presenting author: Ludovico Silvestri, National Institute of Optics (INO-CNR), Via Nello Carrara 1,
50019 Sesto Fiorentino (FI), Italy, phone +390554572504, email [email protected]
Bias modulation for faster Scanning Ion Conductance Microscopy
of biological samples
1
E. Tognoni1, P. Baschieri1, M. Pellegrini2, M. Pellegrino1,3, C. Ascoli1,
National Institute of Optics, UOS Pisa, National Research Council, Italy
2
Scuola Normale Superiore, Pisa, Italy
3
Department for Translational Research, Univ. of Pisa, Pisa, Italy
Abstract
Scanning Ion Conductance Microscopy (SICM) belongs to the family of probe
microscopies. It has been proposed by Hansma and coworkers in 1989, to obtain
topographic images of nonconducting surfaces covered by electrolytic solutions [1]. The
technique is based on the measurement of the ion current generated by applying a
voltage between two electrodes, the first one inserted in the probe (pipette), the second
one placed in the bulk solution. The current decreases when the probe tip approaches
the nonconducting sample surface. Thus, the observed current can be used as a feedback
to keep a given working distance during the scanning over the sample surface. The
recorded path of the probe tip reproduces the sample topography.
Several operation modes have been exploited for SICM imaging: DC current [1], z
oscillation [2], back-step of the probe [3]. The last one is preferred for imaging
biological samples because it prevents any accidental contact between probe and
sample. The vertical approach to specified targets also opens the way to the application
of controlled force to the cell membrane, with the aim of measuring its mechanical
properties or stimulating reactions from particular cells, such as neurons [4,5]. However,
back-step is also the slowest SICM method. Long imaging times are not ideal with
biological samples because they tend to change continuously their morphology. A
solution may be provided by Bias Modulation SICM, which joins the potential for high
speed scanning to the reduction of noise, compared to DC operation [6]. In our
laboratory we are testing Bias Modulation SICM in different configurations, with the
aim of optimizing its performance with biological samples.
References
[1] P.K. Hansma et al., The Scanning Ion-Conductance Microscope, Science, 243 (1989) 641-643.
[2] D. Pastré et al., Characterization of AC mode scanning ion-conductance microscopy, Ultramicrosc, 90
(2001) 13-19.
[3] P. Happel et al., Monitoring cell movements and volume changes with pulse-mode scanning ion
conductance microscopy, J of Microsc, 212 (2003) 144–151.
[4] M. Pellegrino et al., Weak hydrostatic forces in far-scanning ion conductance microscopy used to
guide neuronal growth cones, Neurosci Res 69 (2011) 234–240.
[5] M. Pellegrino et al., Measuring the elastic properties of living cells through the analysis of
current–displacement curves in scanning ion conductance microscopy, Pflugers Arch - Eur J Physiol, 464
(2012) 307–316.
[6] P. Li et al., In-phase bias modulation mode of scanning ion conductance microscopy with capacitance
compensation, IEEE Transactions on Industrial Electronics, 62 (2015) 6508-6518.
Presenting author: Elisabetta Tognoni, INO-UOS Pisa, Via Moruzzi 1- 56124 Pisa, phone +39 050
3152223, fax +39 050 3152576, email: [email protected]
Photonic necklace states in 2d and integrated single quantum
emitters
F. Sgrignuoli1,2, G. Mazzamuto2,3, S. Checcucci 2,3, P. Lombardi 2,3, S. Rizvi 2,3, N.
Caselli1,3, F. Intonti1,3, M.Agio 4,5, M. Gurioli1,3, F.S. Cataliotti1,3,4, C. Toninelli2,3,4
1
Dipartimento di Fisica, Università di Firenze, Via Sansone 1,I-5001 Sesto F.no, Italy
2
CNR-INO, Istituto Nazionale di Ottica, Via Carrara 1, 50019 Sesto F.no, Italy
3
LENS e Università di Firenze, Via Carrara 1, 50019 Sesto F.no, Italy
4
QSTAR, Largo Fermi 2, I-50125 Firenze, Italy
5
Nano-optics Laboratory, University of Siegen, Walter-Flex Strasse 3, 57072 Siegen,
Germany
Abstract
Nowadays, the integration of a single quantum emitter, i.e single photon source,
with different photonic architectures poses a great research challenge. Indeed, this
interconnection can be considered as the heart of various cutting edge research topics,
including cryptography, cavity quantum electrodynamics, and quantum information
networks [1].
In this work, I will first discuss the role of disorder in 2D photonic structures,
constituting a relevant platform for quantum emitter integration and then present results
on the efficient beaming of single molecule by means of robust planar optical antennas.
The term “disorder” in photonic tends to carry a negative stigma. However, it
represents also the common denominator of a plethora of phenomena, characterized by
a multiple-scattering description. In particular, we focus on the interplay between order
and disorder in photonic structures to allow an efficient coupling between otherwise
confined modes. These coupled states, i.e. necklace state, are responsible for transport
in otherwise localizing systems. However, necklace state statistical occurrence in
dimensions higher than one is hard to measure, because of the lack of a decisive
signature. We provide a method to fill this gap. By analysing the phase spatial
probability distribution of the electromagnetic field (PSPD), which is nowadays
obtainable by means of near-field optical microscope measurements, we observe a
bimodal signature of the equivalent necklace states in 2D. We exploit the analogy to a
system of coupled photonic crystal cavities in order to closely relate the double peak in
the PSPD to the coupling between resonant modes. In particular, we study the mode
profile as a function of relative mode detuning and coupling strength [2]. These results
are crucial in enabling a statistical approach, hence to allow controlling composite-mode
effects in random systems.
For the second purpose, we use a multi-layered device with an active layer DBTbased. From a photonic point of view, light detection form a sub-wavelength source can
be regarded as an antenna problem, where the light emitted by a Hertzian dipole has to
be efficiently collected by a receiver. The goal is that of engineering the electromagnetic
environment around the emitter to reduce the directivity of the receiver, i.e. to reduce
the numerical aperture of the collection optics. Both numerical and experimental results
show that the modification of the radiation pattern of a sub-wavelength emitter channels
its emission into a narrow cone, opening a new route into the single-emission detection
scenario.
References
[1] B. Lounis, and M.Orrit, Single-photon sources, Rep. Prog. Phys.,68 (2010) 1129-1179.
[2] F.Sgrignuoli, et al, Necklace State Hallmark in disordered 2D photonic crystals, ACS-Photonics,
(2015) doi: 10.1021/acsphotonics.5b00422.
Presenting author: Fabrizio Sgrignuoli, Via Nello Carrara1, I50019, Sesto F.no, 055-4572389,
[email protected].
A new model for complex dynamics in a dc glow discharge tube
R.Meucci1, E. Pugliese1,2, S.Euzzor1, J. G.Freire3,4 , J. A.C. Gallas1,3,4
1
Istituto Nazionale di Ottica- CNR, Largo E. Fermi 6, 50125 Firenze, Italy
Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira 4,
Firenze, Italy
3
Departamento de Fisica,Universidade Federal da Paraiba, 58051-970 Joao Pessoa,
Brazil
4
Instituto de Altos Estudos da Paraiba, Rua Infante Dom Henrique 100-1801, 58039-150
Joao Pessoa, Brazil
2
Abstract
Based on a detailed experimental characterization of the complex dynamics of a Ne
discharge tube, a new phenomenological model governed by four differential equations
is proposed. Such a model takes into account the competition between a nonlinear
relaxation oscillator related with external electronic features and a forced harmonic
oscillator accounting for the plasma eigenfrequency. From their interaction, the quasi
periodicity route to chaos emerges as confirmed by the experimental observations.
In the control parameter space, stability diagrams for periodic oscillations of arbitrary
period are computed using the isospike technique and compared with standard diagrams
of Lyapunov exponents. Such diagrams reveal complex patterns of stability phases with
extended regions of multistability.
References
[1] E. Pugliese, R. Meucci, S. Euzzor, J.G. Freire, and J. A. C Gallas, Complex dynamics of a dc glow
discharge tube: Experimental modeling and stability diagrams. Nature Sci. Rep, article 08447, (2015).
Presenting author: Riccardo Meucci, Istituto Nazionale di Ottica-CNR, Firenze, Italy. e-mail:
[email protected]
Characterization of ceramic high-temperature solar absorbers
E. Sani1, L. Mercatelli1, M. Meucci1, L. Silvestroni2, D. Sciti2
CNR-INO, National Institute of Optics, Largo E. Fermi, 6, 50125 Firenze (Italy)
2
CNR-ISTEC, Institute of Science and Technology for Ceramics, Via Granarolo 64,
I-48018 Faenza, Italy
1
Abstract
Solar thermal technology is a safe sustainable and cost-effective energy supply.
Presently, the maximum operating temperature of a solar power plant is <800 K due to
degradation of its components. However, the efficiency of solar thermal power plants
increases with increasing working temperatures. Hence, the problem to be solved is the
improvement of the receiver in terms of radiative properties and chemical stability at
high temperature.
Few materials are currently under study for tower solar receivers, mainly for the
volumetric absorber configuration: alumina (Al2O3) [1] and silicon carbide (SiC) [2].
Alumina is an oxide white material characterized by very high thermal stability,
oxidation resistance and high refractoriness, but with a non-optimal sunlight absorption.
SiC is a non-oxide grey semiconductor with good sunlight absorption and high
oxidation resistance, but also characterized by high thermal emittance.
Ultra High Temperature Ceramics (e.g. borides and carbides of early transition
metals) are considered a class of promising materials for application in the aerospace as
thermal protection materials. A novel potential application is in the field of solar thermal
power for solar absorbers. UHTCs possess favorable properties, like the highest melting
points of known materials and good thermo-mechanical properties at high temperatures,
that can be advantageously exploited to increase the operating temperature of
thermodynamic solar plants. This work reports on the optical characterization of several
diborides and carbides, pure or containing secondary phases, to evaluate their potential
as novel solar absorbers.
References
[1] J. Karni, A. Kribus, R. Rubin, P. Doron, The “porcupine”: a novel high-flux absorber for volumetric
solar receivers, J. Solar Energy Eng. 120 (1998), 85-95.
[2] C.C. Agrafiotis et al., Evaluation of porous silicon carbide monolithic honeycombs as volumetric
receivers/collectors of concentrated solar radiation, Solar Energy Materials and Solar Cells 91 (2007)
474-88.
Presenting author: Elisa Sani, Istituto Nazionale di Ottica INO-CNR, largo E. Fermi, 6, 50125 Firenze
(Italy) phone +39-(0)55-23.08.278, fax +39-(0)55-233.77.55, email [email protected]
LED lamp for historical lighthouses
Jafrancesco D., Mercatelli L., Francini F., Sansoni P., Fontani D.
CNR INO Florence - Arcetri
Abstract
The process of replacing halogen or HID sources with LED sources is under development also in the field of
maritime signalling, thanks to the recently updated norms and to the availability of high-power LEDs. The
presentation describes the design, implementation and test of a new LED lamp for lighthouses. In this lamp
the beams from a planar array made of multiple LED + lens assembly are recombined in order to create a
quasi-punctual localized source. With the contribution of the Italian Navy, the lamp was assembled,
mounted in a lighthouse (Tino Island, La Spezia bay) and specific photometric tests verified that the
experimental results agree with the simulation ones. The proposed LED source is more durable and reliable;
moreover, it allows to keep and to utilize the historically-significant old Fresnel lenses of the lighthouse.
The Italian Navy plans to mount an updated version of this lamp on 5-10 lighthouses in the next 12 months,
but in the future the application of these power-saving long-life sources could be extended to other traffic
signalling devices.
Ultrasonic Force Microscopy: mechanical contrast on the
nanoscale for the structural analysis of ultrathin films
F. Dinelli
Istituto Nazionale di Ottica, CNR, Pisa, Italy
Abstract
Scanning probe Microscopy (SPM) represents a powerful tool that in the past thirty years has
allowed the scientific community to widely investigate materials at the nanoscale level.
Generally, it can investigate volumes that are near to the surfaces. A certain degree of
penetration depth has been achieved in just a few cases, namely electronic or magnetic states.
Ultrasonic Force Microscope (UFM) is a variation of Atomic Force Microscope (AFM),
proposed more than twenty years ago as a tool capable of investigating the elasticity of very stiff
materials [1]. Since then it has been shown that UFM can also probe variation of Young’s
modulus due to strain field, phase transition phenomena and sometimes subsurface features
[2,3]. In this presentation I will show some examples of how this technique, combined with
others, can represent a useful tool for the structural analysis of ultrathin films.
Graphene, along with other 2D materials, is increasingly considered for a variety of
Nanotechnology applications. However integrating it within miniaturized devices is not trivial.
In particular engineering the interfaces between graphene and other components would allow
one to control properties such as heat transfer or charge transport. It is therefore more and more
important to investigate and characterize real devices where graphene can be either suspended
or supported. Herein, we present some investigations carried out on single (SLG) and multiple
layer graphene (MLG) samples [3].
The behavior of polymers under confinement is a topic still hot and strongly debated. Recent
experimental evidence has shown that a polymer layer can irreversibly adsorb onto the
supporting substrates, such as the case of polystyrene (PS) on silicon oxide [4]. This may open
the way to tailor the properties of ultrathin films by controlling their adsorption kinetics.
Specifically, UFM can follow the time evolution of such a process. This can be done via
monitoring both the thickness and the elastic contrast of the adsorbed layers as a function of the
annealing time and temperature.
The interfacial properties of polymer blends are highly relevant for properties such as the charge
dynamics in polymer solar cells (PSCs). One of the most common blends used is represented by
the combination of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl
ester (PCBM). It is known that a larger interfacial area for efficient exciton dissociation and a
well-defined p-n junction with few defect levels at the P3HT/PCBM interface are very
beneficial to the device performances. In this case, UFM allows one to determine not only that
the process of phase separation can be controlled by means of thermal annealing but that a
compositional gradient can be created across the P3HT:PCBM films [5].
Understanding the elastic response at the nanoscale phase boundaries of multiferroic films is an
essential issue in order to explain their exotic behaviour. Mixed-phase BiFeO3 (BFO) samples
have been investigated by means of UFM and other techniques such as piezoforce microscopy
(PFM) and X-ray diffraction strain analysis (RSM) to characterize the elastic response at the
boundaries between different crystalline phases. For the first time an elastic modulation in
mixed-phase areas has been resolved at the nanoscale level [7].
References
[1] O. Kolosov and K. Yamanaka, Japan J. of Appl. Phys. Part 2-Letters 32 (8A), (1993) L1095
[2] K. Yamanaka et al. ,Appl. Phys. Lett. 64, (1994) 178
[3] F. Dinelli et al., Phil. Mag. 80, (2000) 2299
[4] C. Housmans et al. Macromolecules 47, (2014) 3390
[5] C.-H. Cheng et al., Scientific Reports 5, (2015) 8091
[6] A. Gruverman, J. Vacuum Science and Technology B 13, (1995) 1095
[7] C.-H. Cheng et al. Japan J. of Appl. Phys. 54, (2015) 122301
Presenting author: Franco Dinelli, Area della Ricerca di Pisa - S. Cataldo, via Moruzzi1, I-56124 Pisa,
Italy; [email protected]; Tel: +39 050 3152564; Fax: +39 050 3152576
Frequency Comb Generation in Quadratic Nonlinear Media
M. Parisi1, I. Ricciardi1, S. Mosca1, P. Maddaloni1, L. Santamaria1, P. De Natale2,
and M. De Rosa1
1
INO-CNR, Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
2
INO-CNR, Largo E. Fermi 6, 50125 Firenze, Italy
The generation of optical frequency Combs in a continuously-pumped
cavity-enhanced second-harmonic-generation system is experimentally demonstrated
and theoretically explained [1,2]. Differently from other configurations where χ(2)
nonlinearity is used to replicate or extend an existing frequency comb, our system
creates entirely new broadband χ(2)-comb emission, both around the fundamental pump
frequency and its second harmonic, starting from a single-frequency pump. The simple
experimental configuration brings to the fore the essential elements that produce the
combs, leading to a deeper understanding of the physics through a quantitative and
concise theoretical model. Despite the different underlying physical mechanism, the
proposed model is remarkably similar to the description of third-order comb generation
in microresonators[3], revealing a potential variety of new effects to be explored and
laying the groundwork for a novel class of highly efficient and versatile frequency comb
synthesizers based on second-order nonlinear materials.
References
[1] I. Ricciardi, S. Mosca, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale and M. De Rosa,
Frequency comb generation in quadratic nonlinear media, Phys. Rev. A 91 063839 (2015).
[2] S. Mosca, I. Ricciardi, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale and M. De Rosa, Direct
generation of optical frequency combs in χ(2) nonlinear cavities, arXiv: 1510.08074 [physics.optics]
(2015).
[3] T. J. Kippenberg, R. Holzwarth, and S. A. Diddams, Microresonator-Based Optical Frequency Combs,
Science 332, 555 (2011).
Presenting author: Maria Parisi, [email protected].
Recent developments of the SCAR apparatus for radiocarbon dioxide
optical detection
I. Galli1,2, S. Bartalini1,2, M. Barucci1, P. Cancio1,2, G. Giusfredi1,2, D. Mazzotti1,2, P. De
Natale1,2
1
Istituto Nazionale di Ottica (INO) - CNR, Sesto Fiorentino FI, Italy
2
European Laboratory for Non-linear Spectroscopy (LENS), Sesto Fiorentino FI, Italy
Abstract
Since 2010 we have been developing in our laboratory a spectroscopic apparatus
based on saturated-absorption cavity ring-down (SCAR), aimed at radiocarbon dioxide
optical detection [1-3]. The first apparatus, which had been designed to carry out a
proof-of-principle experiment, required cryogenic consumables for cooling the highfinesse Fabry-Perot cavity containing the sample gas and relied on a very complex laser
source. Indeed, highly coherent and Cs-traceable mid-IR radiation tunable around 4.5
m was generated by an intra-cavity difference-frequency non-linear process, with the
near-IR pump and signal lasers phase-locked to each other by using an optical
frequency comb synthesizer as a transfer oscillator.
Following what already outlined after a successful intercomparison between SCAR
results and accelerator mass spectrometry (AMS) measurements on the same samples
[4], we have recently modified the SCAR apparatus, designing and building a much
simpler laser setup with a cryogenic-free cooling system for the cavity. Two quantum
cascade lasers (QCLs) are used to fill efficiently the cavity with radiation at 4527 nm.
One of them is frequency locked to a molecular reference line, while the other one is
scanned across the 14CO2 target line. An acoustic-Stirling cryocooler stabilizes the cavity
temperature at 170 K, thus suppressing, down to a negligible level, all interfering lines
belonging to different CO2 isotopologues. The recorded absorption spectra are retrieved
from the detected SCAR decay signals and analyzed by using a theoretical framework
and a fitting routine which take into account all relevant physical phenomena involved
[5].
Preliminary and encouraging results are reported, showing that the sensitivity of this
upgraded SCAR apparatus is at least 5 times better than the first one, thus further
approaching the AMS sensitivity for radiocarbon detection.
References
[1] I. Galli, S. Bartalini, S. Borri, P. Cancio, D. Mazzotti, P. De Natale, and G. Giusfredi, Molecular gas
sensing below parts per trillion: radiocarbon-dioxide optical detection, Phys. Rev. Lett. 107, (2011)
270802; D. Mazzotti, S. Bartalini, S. Borri, P. Cancio, I. Galli, G. Giusfredi, and P. De Natale, All-optical
radiocarbon dating, Opt. Photon. News 23(12), (2012) 52; R. N. Zare, Analytical chemistry:
ultrasensitive radiocarbon detection, Nature 482, (2012) 312.
[2] I. Galli, P. Cancio, G. Di Lonardo, L. Fusina, G. Giusfredi, D. Mazzotti, F. Tamassia, and P. De Natale,
The 3 band of 14C16O2 molecule measured by optical-frequency-comb-assisted cavity ring-down
spectroscopy [Invited article], Mol. Phys. 109, (2011) 2267-2272.
[3] P. Cancio, S. Bartalini, S. Borri, I. Galli, G. Gagliardi, G. Giusfredi, P. Maddaloni, P. Malara, D.
Mazzotti, and P. De Natale, Frequency-comb-referenced mid-IR sources for next-generation
environmental sensors, Appl. Phys. B 102, (2011) 255-269.
[4] I. Galli, S. Bartalini, P. Cancio, P. De Natale, D. Mazzotti, G. Giusfredi, M. E. Fedi, and P. A. Mandò,
Optical detection of radiocarbon dioxide: first results and AMS intercomparison, Radiocarbon 55, (2013)
213-223.
[5] G. Giusfredi, I. Galli, D. Mazzotti, P. Cancio, and P. De Natale, Theory of saturated-absorption cavity
ring-down: radiocarbon dioxide detection, a case study, J. Opt. Soc. Am. B 32, (2015) 2223-2237.
Presenting author: Davide Mazzotti, c/o LENS, Via Carrara 1, 50019 Sesto Fiorentino FI, Tel.: +39-055457-2500, e-mail: [email protected].
Design and characterization of Yb-doped transparent ceramics for
high power laser applications: recent advancements at CNR
G. Toci1, A. Lapucci2, M. Ciofini2, L. Gizzi3, L. Labate3, P. Ferrara3, A. Pirri4 M. Nikl5, J.
7
7
7
1
Li6, L. Esposito , V. Biasini , J. Hostasa , M. Vannini ,
1
Istituto Nazionale di Ottica, CNR, Sesto F.no, Italy
2
Istituto Nazionale di Ottica, CNR, Firenze, Italy
3
Istituto Nazionale di Ottica, CNR, Pisa, Italy
Istituto di Fisica Applicata "Nello Carrara", CNR, Sesto F.no, Italy
5
Institute of Physics, Academy of Sciences, Prague, Czech Republic
6
Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China
7
Istituto di Scienza e Tecnologia dei Materiali Ceramici, CNR, Faenza, Italy
Abstract
The interest on Yb doped laser materials has steadily grown over the last
decade; this success is due to several interesting features:the small quantum defect
(usually around 10%), which results in a low pump power dissipation and then in a low
thermal load and high efficiency; easy pumping with high power semiconductor lasers;
the broad emission spectrum met in several hosts, suitable for the generation and
amplification of fs laser pulses. The large availability of hosts for Yb3+ provides a broad
variability in the material properties, with the possibility of finely tune the choice of the
material according to the specific application needs.
In this scenario, materials based on transparent polycrystalline ceramics are
gaining a growing importance. The ceramics fabrication methods usually require lower
processing temperatures than crystal growth techniques, providing a more convenient
approach for the fabrication of materials with high melting point (e.g. sesquioxides and
some garnets). Moreover the ceramic process is highly flexible in terms of feasible
geometries and shapes, as well as dopant distribution control, allowing technical
solutions which are unfeasible or very difficult to implement with the current crystal
growth technologies.
In this communication we will focus on two recent developments regarding Yb
doped ceramics for laser applications, based on the cooperation among several CNR
institutes and international partners.
The first is the design and development of Yb:YAG ceramics with non uniform,
layered Yb doping distribution, for the management of the thermomechanical stress
induced by the laser pumping process. These structures were designed by means of
Finite Element Analysis [1] and fabricated by means of solid state reactive sintering.
The microstructure and the optical quality of the produced ceramics was characterized
and discussed in connection with the microstructure and laser emission results.
The second development is the realization and characterization of ceramics
with mixed granet composition, namely (LuxY1-x)3Al5O12 (LuYAG), doped with Yb. We
recently obtained for the first time laser emission from a ceramic with this formulation
[2], with a high efficiency and relatively broad tuning range. We will present here the
characterization of their spectroscopic properties and of their laser emission
performance.
References
[1] P. Ferrara, M. Ciofini, L. Esposito, J. Hostaša, L. Labate, A. Lapucci, A. Pirri, G. Toci, M. Vannini,
L.A. Gizzi, 3-D numerical simulation of Yb: YAG active slabs with longitudinal doping gradient for
thermal load effects assessment, Opt. Express, 22, 5375-5386 (2014)
[2] G. Toci, A. Pirri, J. Li, T. Xie, Y. Pan, V. Babin, A. Beitlerova, M. Nikl, M. Vannini, First laser
emission of Yb0.15:(Lu0.5Y0.5)3Al5O12 ceramics, submitted to Opt. Express (2015)
Presenting author: Guido Toci, INO-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy, ph.
+39-0555225315, [email protected]
Gas targets for laser-plasma acceleration applications
F. Brandi1,2 , F. Baffigi1, F. Conti3,4, L. Fulgentini1, F. Giammanco3,4, P. M. Koester1,
L. Labate1,5, F. Sylla6, and L. A. Gizzi1,5
1
Intense Laser Irradiation Laboratory (ILIL), Istituto Nazionale di Ottica (INO-CNR), Via
Moruzzi 1, Pisa, Italy,
2
Istituto Italiano di Tecnologia (IIT), Via Morego 30, Genova, Italy,
3
Plasma Diagnostics&Technology Ltd, Pisa, Italy
4
Dipartimento di Fisica, Università degli Studi di Pisa, Pisa, Italy,
5
INFN, Sezione di Pisa, Italy,
6
SourceLAB SAS, Palaiseaux, France.
Abstract
After several decades of fundamental research on high-intensity laser-plasma
interaction, recent progress on the production of energetic particle beams from
laser-wakefield acceleration (LWFA) has opened the way for actual applications in
future accelerator technology as well as for medical uses including therapy and
diagnosis. To implement these practical applications the full control of the free-electron
density in the plasma, a fundamental parameter in LWFA, is mandatory. In the widely
used and versatile gas targets the free-electron density is substantially related to the
particle number density through photo-ionization. Different kind of gas targets can be
implemented in LWFA experiments. Supersonic gas jets are frequently used as they
allow for generating a flat density profile bounded with steep gradients, whose peak
density is easily tunable by varying the upstream backing pressure. Using a flow gas
cell/capillary enables a stable and manageable laser-plasma interaction process over
long distances, and it is compatible with high-repetition rate laser system. In general
however, the number density in such targets cannot be inferred simply from the applied
backing pressure using ideal gas law, thus a characterization and/or real-time monitor is
needed to implements practical applications of LWFA. The number density in gas
samples can be accurately measured by interferometric techniques. Standard two-arm
interferometers (e.g., Mach-Zender interferometer) are used in many labs for the
characterization of gas targets, but suffer from a high sensitivity on the environmental
conditions and are therefore inadequate for an accurate real-time monitoring over an
extended period of time in practice. The implementation of interferometers which are
quasi-common-path (e.g., Nomarski interferometer) or fully common-path (e.g.
second-harmonic interferometers) reduces the influence of environmental conditions.
In this seminar an overview of practical applications of LWFA and of gas targets used
is given. Two specific gas targets are then discussed in details. Firstly, the
characterization of the supersonic gas jet currently used for LWFA at ILIL in Pisa [1] is
presented along with the planned activity with the modified jet to achieve a tailored
density profile. Secondly, a flow gas cell specifically developed for LWFA applications
by the SourceLAB company (France) is presented, and real-time number density
measurements by common-path second-harmonic interferometry discussed [2].
References
[1] L.A. Gizzi, L. Labate, F. Baffigi, F. Brandi, G.C. Bussolino, L. Fulgentini, P. Koester, D. Palla, and F.
Rossi, Laser–plasma acceleration of electrons for radiobiology and radiation sources, Nuclear
Instruments and Methods in Physics Research B, 355 (2015) 241-245.
[2] F. Brandi, F. Sylla, F. Conti, F. Giammanco and L.A. Gizzi, Real-time characterization of a flow gas
cell for laser wakefield acceleration using second-harmonic interferometry , in preparation.
Presenting author: Fernando Brandi, INO-CNR, Via Moruzzi 1, 56124-PISA, Phone +39050315 2584
Fax. +39 050 315 2247, email [email protected].
Poster session
Near-infrared confocal reflectance imaging as a complimentary tool for
two-photon fluorescence brain imaging
A. L. Allegra Mascaro1,2, I. Costantini1, E. Margoni1, G. Iannello3, A. Bria3,4, L.
Sacconi1,2, F. S. Pavone1,2,5
1
European Laboratory for Non-Linear Spectroscopy (LENS), Florence, Italy,
2
National Institute of Optics (INO-CNR), Sesto Fiorentino (FI), Italy
3
Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
4
Department of Electrical and Information Engineering, University of Cassino, Italy
5
Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
Abstract
Two-photon imaging combined with targeted fluorescent indicators is extensively
used for attaining critical insights into brain functionality and structural plasticity in
vivo. Additional information might be gained from back-scattered photons from the
NIR laser without introducing any exogenous labelling. Here, we describe a
complimentary and versatile approach that, by collecting the reflected NIR light,
provides structural details on the myelinated axons and blood vessels in the brain, both
in fixed samples and in live animals under a cranial windows. Indeed, by combining
NIR reflectance and two-photon imaging of a slice of hippocampus from a Thy1-GFPm
mouse, we show the presence of randomly-oriented axons intermingled with sparsely
fluorescent neuronal processes. The back-scattered photons guide the contextualization
of the fluorescence structure within brain atlas thanks to the recognition of characteristic
hippocampal structures. Interestingly, myelin formations allowed the label-free
detection of axonal elongations over the layer 2/3 of mouse cortex under a cranial
window in vivo. Finally, blood flow can be measured in live preparations, thus
validating label free NIR reflectance as a tool for monitoring haemodynamic
fluctuations. The prospective versatility of this label-free technique complimentary to
two-photon fluorescence microscopy is demonstrated in a mouse model of
photothrombotic stroke in which the axonal degeneration and blood flow remodelling
has been investigated.
Presenting author: Anna Letizia Allegra Mascaro, Via Nello Carrara 1, Sesto Fiorentino, 0554572504,
[email protected].
Whispering-gallery modes in liquid droplet resonators
S. Avino1, R. Zullo1, A. Giorgini1, P. Malara1, P. De Natale2 and G. Gagliardi1
1
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO)
Comprensorio A. Olivetti, via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
2
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO),
Largo E. Fermi 6, 50125 Firenze, Italy
Abstract
Over the last decade, optical whispering-gallery modes (WGMs) have been observed in
solid micro-cavities of various geometries. WGMs supported by dielectric microspheres and
toroids exhibit an optical field that is confined near to the surface [1-3]. Using
highly-transparent glasses, light that is coupled into a WGM can circulate around the resonator
for a long time before being scattered or absorbed. Q factors > 109 can be achieved using silica
material. Silica resonators proved ultra-sensitive bio-chemical probes but were also studied as
miniature systems to observe coupling and interaction phenomena between light and matter
[4-7]. The peculiarity of WGMs is that light travels along closed paths at the interface between
the surface of the resonator and the surrounding environment. Unfortunately, most of the light
circulates inside the resonator and only the evanescent wave tail may interact with the external
medium, i.e. only a small fraction of light is actually used for sensing, thereby reducing the
effective cavity enhancement. Here, we propose to use liquid droplets as micro-resonators for
sensing applications. The droplet itself serves as the sensor and the sample at the same time,
where the internal optical field is directly used to probe dissolved analytes or particles. We
demonstrate free-space excitation and laser frequency locking on whispering-gallery modes in
vertically-suspended mm-size liquid droplets. Photon lifetime measurements are performed by
cavity ring-down techniques recording Q-factors ranging from 5105 to 107 in the near-infrared
and visible spectral regions. Lifetime changes are measured in mixtures made from different
liquids as a proof-of-concept of chemical sensing [8].
References
[1] A. B. Matsk and, V. S. Ilchenko, Optical resonators with whispering-gallery modes - Part I: Basics,
IEEE J. Sel. Top. Quant. 12 (2006) 3-14.
[2] V. S. Ilchenko and A. B. Matsko, Optical resonators with whispering-gallery modes - Part II:
Applications, IEEE J. Sel. Top. Quant. 12 (2006) 15-32.
[3] K. J. Vahala, Optical microcavities, Nature 424 (2003) 839-846.
[4] F. Vollmer and S. Arnold, Whispering-gallery-mode biosensing: label-free detection down to single
molecules, Nat. Methods 5 (2008) 591-596.
[5] J. Zhu, et al. On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh-Q
microresonator, Nat. Photonics 4 (2010) 46-49.
[6] T.J. Kippenberg, R. Holzwarth and S. A. Diddams, Microresonator-Based Optical Frequency Combs,
Science 322 (2011) 555-559.
[7] A. M. Armani, R. P. Kulkarni, S. E. Fraser, R. C. Flagan and K. J. Vahala, Label-free, singlemolecule
detection with optical microcavities. Science 317 (2007) 783-787.
[8] S. Avino, A. Krause, R. Zullo, A. Giorgini, P. Malara, P. De Natale, H.-P. Loock, and G. Gagliardi,
Direct sensing in liquids using whispering-gallery mode droplet resonators, Adv. Opt. Mat. 2 (2014)
1155–1159.
Presenting author: Saverio Avino, CNR - Istituto Nazionale di Ottica (INO), Comprensorio A. Olivetti,
via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy. Tel: +390818675429. E-mail: [email protected].
Photoluminescence, electrical and gas sensing properties of individual
ZnO nanowire in a transistor configuration
F. Rigoni, C. Baratto, M. Donarelli, N. Cattabiani, E. Comini, G. Sberveglieri and G.
Faglia
Sensor Lab, CNR-INO & University of Brescia – Brescia - Italy
Abstract
As wide-bandgap semiconductor, ZnO is a very attractive candidate for blue and UV
optoelectronics [1]. In this work we investigated photoluminescence (PL) properties of
individual ZnO nanowire (NW), prepared by evaporation condensation technique, then
dispersed in isopropanol and transferred on different substrates (as SiO2, SiO2/Si
p-doped, p-GaN, or p-SiC).
The choice of a single nanowire - instead of mesh of nanowires with a wide diameter
distribution - allows to better understand the properties of the material and to investigate
the PL emission properties as a function of the nanowire dimensions. There are many
applications of SMOX materials like n-type ZnO where individual nanowires are
employed: single-wire transistors, gas sensors and, once put in contact with a p-type
materials to create p-n junctions, nano-optoelectronic devices, e.g. UV LED.
PL maps of single nanowires show that as the diameter of the wire decreases, a shift
in the near band edge (NBE) PL is observed, in accordance with Ref. [2].
Temperature dependent PL spectra (from RT to 77 K) of ZnO single NW has been
carried out in order to assign peaks corresponding to free exciton (FX), donor bound
exciton (DX) and LO-assisted FX [3] and to reach insight on the mechanism responsible
for PL emission of the nanowires as the diameter changes.
Pt contacts has been deposited by electron beam lithography (EBL) on the single ZnO
NW. This allows us to obtain PL information as a function of the current flowing in the
NW or, in FET configuration, as function of gate voltage applied.
Finally, the deposition of n-type ZnO NWs on different substrates, in particular on
p-type substrates, allows to observe heterojunction effects at the nanoscale level which
play a crucial role in the perspective of ZnO based nano-optoelectronic devices
production.
References
[1]. J. Bao, M.A. Zimmler, F. Capasso, Z. Wang, and Z.F. Ren, Broadband ZnO single-nanowire
light-emitting diode. Nano Letters, 2006. 6: p. 1719-1722.
[2]. X. Zhang, D. Liu, L. Zhang, W. Li, M. Gao, W. Ma, Y. Ren, Q. Zeng, Z. Niu, W. Zhou, and S. Xie,
Synthesis of large-scale periodic ZnO nanorod arrays and its blue-shift of UV luminescence. J. Mater.
Chem., 2009. 19: p. 962-969.
[3]. D.W. Hamby, D.A. Lucca, M.J. Klopfstein, and G. Cantwell, Temperature dependent exciton
photoluminescence of bulk ZnO. J. of applied Physics, 2003. 93: p. 3214-3217.
Presenting author: Camilla Baratto, Sensor Lab, CNR-INO, Via Branze 45, 25133 Brescia, tel.
030-3715706, email: [email protected]
Gas targets for laser-plasma acceleration applications
F. Brandi1,2 , F. Baffigi1, F. Conti3,4, L. Fulgentini1, F. Giammanco3,4, P. M. Koester1,
L. Labate1,5, F. Sylla6, and L. A. Gizzi1,5
1
Intense Laser Irradiation Laboratory (ILIL), Istituto Nazionale di Ottica (INO-CNR), Via
Moruzzi 1, Pisa, Italy,
2
Istituto Italiano di Tecnologia (IIT), Via Morego 30, Genova, Italy,
3
Plasma Diagnostics&Technology Ltd, Pisa, Italy
4
Dipartimento di Fisica, Università degli Studi di Pisa, Pisa, Italy,
5
INFN, Sezione di Pisa, Italy,
6
SourceLAB SAS, Palaiseaux, France.
Abstract
After several decades of fundamental research on high-intensity laser-plasma
interaction, recent progress on the production of energetic particle beams from
laser-wakefield acceleration (LWFA) has opened the way for actual applications in
future accelerator technology as well as for medical uses including therapy and
diagnosis. To implement these practical applications the full control of the free-electron
density in the plasma, a fundamental parameter in LWFA, is mandatory. In the widely
used and versatile gas targets the free-electron density is substantially related to the
particle number density through photo-ionization. Different kind of gas targets can be
implemented in LWFA experiments. Supersonic gas jets are frequently used as they
allow for generating a flat density profile bounded with steep gradients, whose peak
density is easily tunable by varying the upstream backing pressure. Using a flow gas
cell/capillary enables a stable and manageable laser-plasma interaction process over
long distances, and it is compatible with high-repetition rate laser system. In general
however, the number density in such targets cannot be inferred simply from the applied
backing pressure using ideal gas law, thus a characterization and/or real-time monitor is
needed to implements practical applications of LWFA. The number density in gas
samples can be accurately measured by interferometric techniques. Standard two-arm
interferometers (e.g., Mach-Zender interferometer) are used in many labs for the
characterization of gas targets, but suffer from a high sensitivity on the environmental
conditions and are therefore inadequate for an accurate real-time monitoring over an
extended period of time in practice. The implementation of interferometers which are
quasi-common-path (e.g., Nomarski interferometer) or fully common-path (e.g.
second-harmonic interferometers) reduces the influence of environmental conditions.
In this seminar an overview of practical applications of LWFA and of gas targets used
is given. Two specific gas targets are then discussed in details. Firstly, the
characterization of the supersonic gas jet currently used for LWFA at ILIL in Pisa [1] is
presented along with the planned activity with the modified jet to achieve a tailored
density profile. Secondly, a flow gas cell specifically developed for LWFA applications
by the SourceLAB company (France) is presented, and real-time number density
measurements by common-path second-harmonic interferometry discussed [2].
References
[1] L.A. Gizzi, L. Labate, F. Baffigi, F. Brandi, G.C. Bussolino, L. Fulgentini, P. Koester, D. Palla, and F.
Rossi, Laser–plasma acceleration of electrons for radiobiology and radiation sources, Nuclear
Instruments and Methods in Physics Research B, 355 (2015) 241-245.
[2] F. Brandi, F. Sylla, F. Conti, F. Giammanco and L.A. Gizzi, Real-time characterization of a flow gas
cell for laser wakefield acceleration using second-harmonic interferometry , in preparation.
Presenting author: Fernando Brandi, INO-CNR, Via Moruzzi 1, 56124-PISA, Phone +39050315 2584
Fax. +39 050 315 2247, email [email protected].
Phase transitions at negative Boltzmann temperature in discrete
nonlinear systems
P. Buonsante1,2, R. Franzosi1,2, A. Smerzi1,2
1
INO, Firenze, Italia
2
QSTAR Center, Firenze, Italia
Abstract
We focus on a class of nonlinear lattice models standardly employed in the description
of the propagation of light through arrays of waveguides, and the dynamics of ultracold
bosons trapped in optical lattices. We consider both the standard “cubic” nonlinearity
and the saturable nonlinearity characterizing optically induced photonic crystals.
We find that, for a suitable sign of the nonlinearity, both choices support states at
negative Boltzmann temperature. However, only saturable nonlinearity supports both
positive– and negative-temperature states in the same lattice system. Even more
interestingly, we show that the same physical sample can in principle undergo phase
transitions for critical energies both in the lower and in the upper portion of the
(bounded) energy spectrum, i.e. for both signs of the Boltzmann temperature.
Two-dimensional optically induced photonic lattices provide an ideal testbed for these
predictions. For self-focusing nonlinearity we expect a self-trapping phase transition at
low positive temperatures (low energies) and a BKT transition at low negative
temperatures (high energies). The transitions are swapped in the defocusing case.
We emphasize that these system have been realized experimentally, and the possibility
of exciting states in the upper portion of the energy band –i.e. negative-temperature
states–, has been already demonstrated. Also, signatures of the ordering relevant to
these above mentioned transitions have already been observed.
References
[1] P. Buonsante, R. Franzosi, A. Smerzi, Phase transitions at high energy vindicate negative
microcanonical temperature, arXiv:1506.01933.
Presenting author: Pierfrancesco Buonsante, QSTAR
[email protected]; [email protected].
Center, Largo Fermi 2 - Firenze,
Dynamics of a fermionic superfluid in a double-well potential
G. Valtolina1,2,3, A. Burchianti1,2, A. Amico1,2,4, C. Fort1,2,4, E. Neri1,2,4, F. Scazza1,2, A.
Smerzi1,2,5, M. Zaccanti1,2, M. Inguscio2,4,6, G. Roati1,2
1
INO-CNR Istituto Nazionale di Ottica del CNR, 50019 Sesto Fiorentino, Italy
2
LENS European Laboratory for Nonlinear Spectroscopy, 50019 Sesto Fiorentino, Italy
3
Scuola Normale Superiore, 56126 Pisa, Italy
4
Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino,
Italy
5
QSTAR Quantum Science and Technology in Arcetri, 50125 Firenze, Italy
6
INRIM Istituto Nazionale di Ricerca Metrologia, 10135 Torino, Italy
Abstract
We study the dynamics of a Josephson junction based on a fermionic superfluid in a
double-well potential. We prepare a two-component 6Li degenerate quantum gas [1] in
an optical dipole trap which is split in two parts by adding an optical barrier. A particle
current flow is induced through the barrier by applying a chemical potential difference
between the two wells. We explore different regimes, ranging from a BEC of a
molecules to a BCS superfluid, by magnetically controlling the two-spin interaction by
means of a Fano-Feshbach resonance. Coherent oscillations are observed across the
whole BEC-BCS crossover [2]. The Josephson regime is then shifted to a dissipative
one by increasing the superfluid velocity. Indeed, above a critical value vortices are
nucleated at the barrier position and eventually propagate in the superfluid bulk, giving
rise to a resistive flow. We found that both the Josephson current and the critical
velocity for vortex generation exhibit a maximum at the unitarity, confirming the
superfluidity robustness for resonant atomic interactions [3]. Furthermore, we show that
our set-up allows to study the transport of spin currents generated by spatially
separating two spin components in the two wells and then letting them to expand.
References
[1] A. Burchianti, G. Valtolina, J. A. Seman, E. Pace, M. De Pas, M. Inguscio, M. Zaccanti, and G. Roati,
Efficient all-optical production of large 6Li quantum gases using D1 gray-molasses cooling, Phys. Rev. A
90, (2014) 043408.
[2] G. Valtolina, A. Burchianti, A. Amico, E. Neri, K. Xhani, J. A. Seman, A. Trombettoni, A. Smerzi, M.
Zaccanti, M. Inguscio and G. Roati, Josephson effect in fermionic superfluids across the BEC-BCS
crossover, arXiv:1508.00733, (2015).
[3] D. E. Miller, J. K. Chin, C. A. Stan, Y. Liu, W. Setiawan, C.Sanner, and W. Ketterle, Critical velocity
for Superfluid Flow across the BEC-BCS crossover, Phys. Rev. Lett. 99 (2007) 070402.
Presenting author: Alessia Burchianti, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy,
+390554572458, [email protected].
In vivo fluorescent bioassay for investigating the mechanisms at the
basis of Alzheimer’s disease
1
M. Calamai1,2, N. Parenti2, F. S. Pavone2
National Institute of Optics, National Research Council of Italy (CNR), Largo Fermi 6,
50125, Florence, Italy
2European
Laboratory for Non-linear Spectroscopy (LENS), University of Florence,
Florence, Italy 50019
Abstract
It is now widely accepted that oligomers consisting of Abeta peptide are the cytotoxic
species contributing mostly to the development of Alzheimer’s disease (AD). Abeta
peptide production results from the specific cleavage of the amyloid precursor protein
(APP). (APP) is a transmembrane protein that can be cut alternatively by other proteins,
called secretases. The sequential cut of APP by two of these secretases, the beta and
gamma, leads to the production of toxic Abeta peptide. By contrast, a secretase called
alpha is responsible for the generation of a harmless Abeta fragment. Most of the
pharmaceutical research effort to challenge AD is nowadays directed at reducing the
amyloid cytotoxic burden by active or passive immunization against Abeta oligomers.
Sadly, these approaches did not succeed in clinical trials. It is imperative therefore to
discover new factors situated upstream of the cleavege of APP that can be used as
therapeutic targets.
In order to address this issue, we have produced a genetically modified APP with a
red fluorescent protein attached at the extremity of the extracellular domain, and a green
fluorescent protein on the intracellular domain. Without cleavage the ratio between the
red and green fluorescence signal is 1. When the alpha or beta secretase cuts the
recombinant APP in a living cell, the red fluorescent protein is released in the
extracellular medium and the green/red ratio changes. By using a particular type of
RNA it is possible to follow the activity of just alpha or beta secretase. This simple but
efficient approach allows to monitor directly in living cells the proteolysis of APP,
outperforming the bulk results obtainable with commercial kits thanks to the high
sensitivity of fluorescence microscopy, and overcoming the limitations of standard
enzymatic activity tests of secretases from cells lysates in vitro. For example, we can
distinguish if the proteolytic processing of APP is homogeneous or not within the same
single cell, a very important point when considering a structurally complex cell such as
the neuron. This method has enabled us to study in an unbiased way the effect of drugs
or particular conditions on APP proteolysis. In particular, we have directly investigated
the role of cholesterol on APP proteolysis. The binding and interaction of APP with
individual secretases seems to be influenced by the levels of cholesterol. Cholesterol
can change the chemical-physical features of the cell membrane, causing the association
or separation of secretases and APP. We have found that higher level of cholesterol, or
decreased levels after treatment with statins (lipid lowering drugs), can effectively alter
the cleavage rate of APP. This is very important as, although many studies support a
correlation between hypercholesterolemia and higher risk to develop AD, the use of
statins in clinical trials has led to unclear and highly debated results.
Overall, this tool based on the ratiometric measurement of fluorescence intensity
constitutes a novel platform for drug screening studies on the secretases. The results
originating from this study will contribute to unveil novel therapeutic strategies.
Presenting author: Martino Calamai, CNR INO-UOS Sesto F.-LENS - European Laboratory for
Non-Linear Spectroscopy, Via Nello Carrara 1 - I 50019 Sesto-Fiorentino (Firenze) - Italia
Telephone: +39 055 4572479 - Fax: +39 055 4572451 Email: [email protected]
Cavity optomechanics with a functionalized silicon nitride membrane
F. Fogliano1, A. Ortu1, A. Camposeo2,, D. Pisignano2,3,,
E. Arimondo1,4,5, F. Fuso1,4,5, D. Ciampini1,4,5
1
Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3,
56127 Pisa, Italy
2
Istituto Nanoscienze-CNR, Euromediterranean Center for Nanomaterial Modelling and
Technology (ECMT), via Arnesano I-73100, Lecce, Italy
3
Dipartimento di Matematica e Fisica ‘Ennio De Giorgi’, Università del Salento,
Arnesano I-73100 Italy
4
INO-CNR, Via G. Moruzzi 1, 56124 Pisa, Italy
5
CNISM UdR Pisa, Dipartimento di Fisica E. Fermi, Università di Pisa, Largo
Pontecorvo 3, I-56127 Pisa, Italy
Abstract
The optomechanical handling of objects with dimensions from nanoscale to
mascroscopic scale is a very active research area, as presented in a recent review by
Aspelmeyer et al. [1]. The range of applications is very wide, starting from quantum
computation with hybrid qubits optomechanically coupled, and arriving to the
controlled motion for macroscopic objects, for instance in gravitational wave detection.
An important component of the research effort is the search for new materials and new
optomechanical processes.
We investigate the optomechanical properties of a cavity containing, as a mirror, a
multilayer membrane composed by tris(8-hydroxyquinoline) aluminum (Alq3), silver
and silicon nitride. Alq3 is an organic semiconductor, while silver has been employed to
enhance the reflectivity; the thikness of the membrane is below 200 nm. We realize a
local optical measurement of the membrane deformation, and perform a tomographic
reconstruction of the whole optomechanics response. We employ two different
wavelengths, one centred within the Alq3 absorption band and a second one outside that
band in order to isolate the optomechanical contribution of the organic semiconductor.
We observe photothermal cooling of the fundamental mode of the membrane, through
the modification of the effective damping rate and the frequency of the membrane
acoustic motion. Variation in the optomechanical parameters leads the system into a
nonlinear dynamics regime, corresponding to self-oscillations at the fundamental
mechanical mode.
References
[1] M. Aspelmeyer, T. J. Kippenberg, and F. Marquardt, Cavity optomechanics, Rev. Mod. Phys., 86
(2014) 1392-1451.
Presenting author: Donatella Ciampini, Dipartimento di Fisica “E. Fermi”, Largo Pontecorvo 3, 56127
Pisa (PI), Italy, phone: +39 050 2214522, fax: +39 050 2214333, [email protected]
Creation, dynamics and interactions
of solitonic vortices in elongated BECs
S.Serafini, M.Barbiero, M.Debortoli, S.Donadello, F.Larcher, F.Dalfovo, G.Lamporesi,
and G. Ferrari
INO-CNR BEC Center and Dipartimento di Fisica, Universita' di Trento, Italy
We study the real-time dynamics of vortices in a large elongated Bose-Einstein
condensate (BEC) of sodium atoms using a stroboscopic technique. Vortices are
produced via the Kibble-Zurek mechanism in a quench across the BEC transition and
they slowly precess keeping their orientation perpendicular to the long axis of the trap
as expected for solitonic vortices in a highly anisotropic condensate. Good agreement
with theoretical predictions is found for the precession period as a function of the orbit
amplitude and the number of condensed atoms. In configurations with two or more
vortices, we see signatures of vortex-vortex interaction in the shape and visibility of the
orbits. In addition, when more than two vortices are present, their decay is faster than
the thermal decay observed for one or two vortices. The possible role of vortex
reconnection processes is discussed.
Reference
S.Serafini, M.Barbiero, M.Debortoli, S.Donadello, F.Larcher, F.Dalfovo, G.Lamporesi, and G.Ferrari,
Phys. Rev. Lett. 115, 170402 (2015)
Presenting author: Franco Dalfovo, INO-CNR BEC Center and Dipartimento di Fisica, Universita' di
Trento, Italy, [email protected]
Towards a quantum degenerate gas of Dysprosium:
a quantum simulator for magnetic dipolar systems
A. Fioretti1, C. Gabbanini1, S. Gozzini1
1
Istituto Nazionale di Ottica, C.N.R., UOS Pisa, via Moruzzi 1, 56124, Pisa, Italy
L. del Bino2, J. Catani2,3, G. Modugno2,3, M. Inguscio2,4, E. Lucioni2,3
2
LENS and Dip. di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
3
Istituto Nazionale di Ottica,CNR, UOS Sesto Fiorentino, 50019 Sesto Fiorentino, Italy
4
INRIM, 10135 Torino, Italy
Dipolar interaction has been predicted to give rise to a wealth of peculiar quantum
phenomena and exotic quantum phases, encompassing supersolids, quasi-crystals,
frustated crystals and self-assembeld structures, so far only barely explored. These
phenomena are due to the combination of the long-ranged and anisotropic nature of
such interaction. Quantum dipolar systems have been so far only barely explored and a
controlled experimental environment is therefore of general interest. Ultracold atomic
gases are emerging as quantum simulators of complex phenomena thanks to their high
degree of tunability and control of the parameters. Notably the possibility to engineer
with light defect-free lattices for atomic gases is allowing to investigate paradigmatic
phenomena related to condensed matter physics in different dimensionalities.
We are currently building an experimental apparatus for the production of quantum
degenerate gases of Dysprosium atoms. Contrary to alkali atoms, usually employed in
cold atoms experiments, Dysprosium has a large magnetic dipole moment, 10 Bohr
magnetons, the largest among all elements. For this reason, besides interacting via van
der Waals interaction, which has substantially a contact nature, Dy atoms also interact
via dipole-dipole magnetic interaction. At present an atomic beam emitted from an
effusive oven is slowed with laser light at 421nm in a Zeeman slower. The slowed
atoms will soon be catched in a magneto-optical trap, which works on a narrow atomic
transition at 626nm, and subsequently transferred in a far-detuned optical trap. Here,
evaporative cooling will be performed, allowing to reach either Bose Einstein
condensation or a Fermi quantum degeneracy in the case of the Fermion isotopes.
This experiment is a joint effort of teams from both the Pisa and the Sesto Fiorentino
(at LENS) sections of the INO-CNR.
Presenting author: Andrea Fioretti, INO-CNR, via Moruzzi 1, 56124 Pisa, tel +050 3152528, email:
[email protected]
The Calibration System of the new muon g-2 experiment at Fermilab:
the construction phase
A. Fioretti1,2, A. Anastasi1,3, D. Babusci1, G. Cantatore4,7, D. Cauz4,9,
S. Dabagov1, G. Di Sciascio6, R. Di Stefano5,10, C. Ferrari1,2, C. Gabbanini1,2,
D. Hampai1, M. Iacovacci5,8, M. Karuza4,11, F. Marignetti5,10, S. Mastroianni8,
D. Moricciani6, G. Pauletta4,9, L. Santi4,9,G. Venanzoni1
1
Laboratori Nazionali Frascati dell' INFN, Via E. Fermi 40, 00044 Frascati, Italy
Istituto Nazionale di Ottica del C.N.R., UOS Pisa, via Moruzzi 1, 56124, Pisa, Italy
3
Dipartimento di Fisica e di Scienze della Terra, Universita di Messina, Messina, Italy
4
INFN, Sezione di Trieste e G.C. di Udine, Italy
5
INFN, Sezione di Napoli, Italy
6
INFN, Sezione di Roma Tor Vergata, Roma, Italy
7
Università di Trieste, Trieste, Italy
8
Università di Napoli, Napoli, Italy
9
Università di Udine, Udine, Italy
10
Università di Cassino, Cassino, Italy
11
University of Rijeka, Rijeka, Croatia
2
Abstract (maximum one page)
The muon anomaly a=(g-2)/2 is a low-energy observable, which can be both
measured and computed to high precision [1]. Therefore it provides an important test of
the Standard Model (SM) and it is a sensitive search for new physics [2].
The muon anomaly (g−2)μ/2 has been measured to 0.54 parts per million by E821
experiment at Brookhaven National Laboratory, and at present there is a 3 to 4
standard-deviation difference between the Standard Model prediction and the
experimental value [3]. A new muon g-2 experiment, E989, is being prepared at
Fermilab that will improve the experimental error by a factor of four to clarify this
difference [4]. A central component to reach this fourfold improvement in accuracy is
the high-precision laser calibration system which should monitor the gain fluctuations
of the calorimeter photodetectors at 0.04% accuracy during the fill time (700 micros).
Over the longer data collection period the goal is to keep systematics contributions due
to gain fluctuations at the sub-percent level. This is a challenge for the design of the
calibration system because the desired accuracy is at least one order of magnitude
higher than that of all other existing, or adopted in the past, calibration systems for
calorimetry in particle physics.
We report here the requirements and the achieved solution of this system. The test
phase of the calibration system has been almost completed. The construction phase at
FNAL is expected to take place in spring 2016.
References
[1] F. Jegerlehner, The anomalous magnetic moment of the muon, Berlin, Springer (2008) 426 p (Springer
tracts in modern physics. 226)
[2] D. Stockinger, Muon (g-2) and physics beyond the standard model, In Roberts, Lee B., Marciano,
William J. (eds.): Lepton dipole moments 393-438 (Adv. series on directions in high energy physics. 20)
[3] H. N. Brown et al. Muon g-2 Collaboration, Phys. Rev. Lett. 86, 2227 (2001).
[4] New Muon (g 2) Collaboration, R.M. Carey et. al., see
http://lss.fnal.gov/archive/testproposal/0000/fermilab-proposal-0989.shtml
Presenting author: Andrea Fioretti, INO-CNR, via Moruzzi 1, 56124 Pisa, tel +050 3152528, email:
[email protected]
Synthesis and Properties of Metal Oxide Nanotubes for
Applications in Security and Environmental Monitoring
V. Galstyan1,2, E. Comini2,1, A. Ponzoni1,2, C. Baratto1,2, V. Sberveglieri1,
N. Poli2, G. Faglia2,1, G. Sberveglieri1,2
1
Sensor Lab, CNR, National Institute of Optics (INO), Via Valotti 9, 25133
Brescia, Italy
2
Sensor Lab, Department of Information Engineering, University of Brescia, Via Valotti
9, 25133 Brescia, Italy
Abstract
Detection of minor gas leaks, harmful chemical vapors and explosives in
environment has been a challenging research problem for many decades as it involves
health, safety and environmental risks. However, gas sensor technologies are still
developing and have yet to reach their full potential in capabilities and usage. Wide
bandgap semiconducting metal oxides (MOXs) are attractive materials for the detection
of explosive, hazardous and toxic gases due to changes in their conductance when
oxidizing or reducing species in air chemisorb onto their surface [1]. These conductivity
changes are exploited for fabrication of chemiresistive chemical sensors based on
MOXs [2].
Herein, we report synthesis and gas sensing properties of TiO2 nanotubes. The
structures were obtained by means of the electrochemical anodization of metallic Ti thin
films. Anodization was carried out by potentiostatic mode in the electrolytes with the
different viscosities using a two-electrode configuration. The formation and the growth
mechanism of obtained tubular structures were investigated. Obtained nanostructures
were analyzed by means of SEM, AFM, micro-Raman spectroscopy and XRD. The
nanostructures’ sensing properties have been tested in a wide range of operating
temperatures towards H2, CO, NO2, acetone and ethanol. The structures’ response is
quite high and the recovery of the signal is almost complete. The preliminary results
show that TiO2 nanotubes are promising structures for the development of gas sensing
devices and electronic noses.
Figure 1. (a) SEM image of the surface of the tubular arrays, (b) the cross-sectional view of TiO2
nanotubes, (c) high magnification SEM image of a single tube and (d) response of the structure towards
100 ppm of acetone, CO, ethanol at a working temperature of 300°C and 40%RH@20°C.
References
[1] A. N. Yamazoe, K. Shimanoe, Theory of power laws for semiconductor gas sensors, Sens. Actuators
B: Chemical, 128 (2008) 566–573.
[2] V. Galstyan, E. Comini, C. Baratto, A. Ponzoni. M. Ferroni, N. Poli, G. Faglia, E. Bontempi, M.
Brisotto, G. Sberveglieri, G. Large surface srea biphase titania for chemical sensing, Sensors and
Actuators B: Chemical, 209, (2015) 1091-1096.
Presenting author: Vardan Galstyan, Sensor Lab, CNR-INO and University of Brescia, Via
Valotti 9, 25133 Brescia, Italy, phone +39 0303715702, fax +39 0302091271, email
[email protected].
Investigations and new approaches in Surface Plasmon Resonance
based optical bio-chemical sensors
A. Giorgini1, R. Zullo1, S. Avino1, P. Malara1, P. De Natale2, G. Gagliardi1
1
1INO-CNR, Pozzuoli, Napoli, Italy
2
INO-CNR, Firenze, Italy
Surface Plasmon Resonance (SPR)-based sensors represent a powerful investigation
tool in chemical and biochemical research [1]. Their advantage stands in the high
sensitivity performances and the possibility of real-time label-free, selective sensing
protocols. The short penetration depth of plasma waves allows to probe the chemical
activity in an extremely thin layer (~300nm) near a metal-dielectric interface.
Nevertheless, the detection of low-weigth molecules (<400Da) at low concentrations
(pM) or of heavy targets with low copy number by SPR is still challenging. Many
efforts have been spent in improving the detection limits of SPR sensors by on-chip
engineering methods or by improving the immobilization protocols [2]. Even in
state-of-the-art sensors, the main limiting factor is represented by the intrinsic
fluctuations of the light source [3]. In this work we present recent experimental
investigations on new approaches for SPR sensing.
Typical techniques derived from laser spectroscopy and from frequency metrology are
applied. The SPR sensing element (chip), mounted in a Kretschmann configuration, is
used as an intermediate mirror of an optical resonator [4,5]. The investigated sample is
delivered to the chip sensing surface by a custom made microfluidic apparatus. The
optical system is interrogated by a single wavelegth laser source kept locked to a
selected cavity mode. Presently, two different methods are implemented and evaluated
in terms of performances. The first is based on time-domain measurements: the
variations of the SPR coupling condition are detected through changes in the cavity
photon lifetime (Cavity Ring down Technique[6]). The second method is based on
frequency domain measurements. In this case transverse-magnetic polarized field (TM),
that interacts with plasma waves, and transverse-electric (TE) polarized field (that has
zero SPR coupling in our geometry), are simultaneously injected in the resonator as
probe and reference fields. Variations of the SPR coupling conditions are transduced
into variations of the real part of the TM field refractive index, and detected by
monitoring the resonator birifringence. The measured observable is in this case the beat
frequency between the TM and TE resonant modes.
References
[1] J. Homola, Surface plasmon resonance based sensors, Springer, 4 (2006).
[2] P. Adam, M. Piliarik, H. Šípová, T. Špringer, M. Vala, J. Homola, Surface Plasmons for Biodetection,
in Photonic Sensing: Principles and Applications for Safety and Security Monitoring, G. Xiao & W. Bock,
(Eds.), John Wiley & Sons (2012) 1-58.
[3] M. Piliarik and J. Homola, Surface plasmon resonance (SPR) sensors: approaching their limits?,
Optics express, 17.19 (2009) 16505-16517.
[4] A. Giorgini, et al. "Surface plasmon resonance optical cavity enhanced refractive index sensing."
Optics letters, 38.11 (2013): 1951-1953.
[5] A. Giorgini, et al. , Cavity-enhanced surface-plasmon resonance sensing: modeling and performance,
Measurement Science and Technology, 25.1 (2014): 015205.
[6] D. Romanini, A.A. Kachanov, N. Sadeghi, F. Stoeckel, CW cavity ring down spectroscopy, Chemical
Physics Letters, 264 .3–4, (1997), 316–322.
Presenting author: Antonio Giorgini, Via Campi Flegrei 34, Pozuoli, Napoli, phone +39 081 8675 415,
fax +39 081 867 5420, email [email protected]
High contrast electromagnetically induced absorption in thermal
potassium cells with spin-preserving coating
S. Gozzini1, A. Fioretti1, A. Lucchesini1, L. Marmugi1,2, C. Marinelli1,3,
S. Tsvetkov4, S. Gateva4, S. Cartaleva4
1
INO CNR – Sede Secondaria di Pisa, Via Moruzzi 1, 56124 Pisa, Italy
2
Dept. of Physics and Astronomy, UCL, Gower Street, London WC1E 6BT, UK
3
CNISM and DFSTA, University of Siena, via Roma 56, 53100 Siena, Italy.
4
Institute of Electronics, BAS, 72 Tzarigradsko Chaussee blvd., 1784 Sofia, Bulgaria
Abstract
Electromagnetically Induced Transparency (EIT) has many applications in
laser physics, precision laser spectroscopy, quantum information, all-optical
magnetometers, miniaturized atomic clock, etc. The opposite effect, the
Electromagnetically Induced Absorption (EIA), still potentially interesting in fields as
the enhancement of the group velocity of the light (“fast” light), metamaterials for novel
photonic devices has found limited applications, mainly due to its worse performances
in terms of linewidth and contrast [1]. We report on a new experimental approach which
allows an order of magnitude EIA resonance contrast. Such a performance is
comparable to what observed under the same conditions with EIT.
In the experiment two counter-propagating beams are arranged to perform
Saturated Absorption (SA) on the D1 line of 39K vapor contained in a cell with
polydimethyl-siloxane (PDMS) antirelaxation coating, which has demonstrated to be
very effective in reducing the resonance linewidth [2]. The transmission signals are
obtained by slowly sweeping the laser across the resonance and in the meanwhile
scanning a magnetic field orthogonal to the laser beams around the zero value at a
frequency rate about on order of magnitude higher. Coherent resonances appear on the
absorption profile at the zero value of the transverse magnetic field (Hanle
configuration). With both laser beams linearly polarized, an EIT resonance is observed
as expected. However, changing the pump beam polarization from linear to circular, the
resonance signal reverses from EIT to EIA, as the results of the interaction of the low
intensity probe beam with the ground atomic state that has been driven in Hanle
configuration by the pump laser beam.
New experimental protocols and arrangements based on the present results can
be thus envisioned, in order to broaden the range of applications of EIA and enhance its
effectiveness.
References
[1] D V Brazhnikov, A V Taichenachev, A M Tumaikin and V I Yudin
Electromagnetically-induced-absorption resonance with high contrast and narrow width in the Hanle
configuration, Laser Phys. Lett., 11 (2014) 125702 (8pp)
[2] K. Nasyrov, S. Gozzini, A. Lucchesini, C. Marinelli, S. Gateva, S. Cartaleva, and L. Marmugi
Antirelaxation coatings in coherent spectroscopy: Theoretical investigation and experimental test Phys.
Rev. A, 92, (2015) 043803-10
Presenting author: Silvia Gozzini, Istituto Nazionale di Ottica - SS di Pisa, Via Moruzzi, 1, 56124 Pisa,
Phone: +39-050-6212526, fax: 39-050-3152522, email: [email protected].
Kinetic constraints in out-of-equilibrium Rydberg gases
M.M. Valado1,2, C. Simonelli1,2, I. Lesanovsky3, J. Garrahan3, E. Arimondo1,2,4, D.
Ciampini1,2,4, O. Morsch1,2
1
Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy
2
INO-CNR, Via G. Moruzzi 1, 56124 Pisa, Italy
3
School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
4
CNISM UdR Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa,
Italy
Abstract
Cold atoms excited to high-lying Rydberg states [1] exhibit a variety of intriguing effects such
as the dipole blockade [2] and facilitated off-resonant excitation [3,4], which are both due to the
strong van der Waals interaction between the atoms. In the present work [5] we experimentally
demonstrate out-of-equilibrium dynamics in such systems that are mediated by an atomic
physics analogue of kinetic constraints. Kinetic constraints were first conceived to model soft
matter systems [6], which exhibit slow and often complex relaxation to equilibrium. Rydberg
gases can be used to simulate the many-body dynamics of soft matter systems, and the kinetic
constraints leading to it can be controlled through the frequency of the excitation lasers [7,8].
Our experimental findings agree well with numerical simulations of a simple model based on an
Ising chain, in which the internal states of the Rydberg atoms are represented as interacting
spins.
References
[1] R. Loew et al., J. Phys. B: At. Mol. Opt. Phys. 45, 113001 (2012).
[2] D. Comparat and P. Pillet, J. Opt. Soc. Am. B 27, A208 (2010).
[3] H. Schempp et al., Phys. Rev. Lett. 112, 013002 (2014).
[4] N. Malossi et al., Phys. Rev. Lett. 113, 023006 (2014).
[5] M.M. Valado et al., arXiv:1508.04384 (2015).
[6] F. Ritort and P. Sollich, Adv. Phys. 52, 219 (2003).
[7] I. Lesanovsky and J.P. Garrahan, Phys. Rev. Lett. 111, 215305 (2013).
[8] I. Lesanovsky and J.P. Garrahan, Phys. Rev. A 90, 011603(R) (2014).
Presenting author: Oliver Morsch, INO-CNR, Via G. Moruzzi 1, 56124 Pisa, Italy, Tel.: 050-2214569,
Fax: 050-2214333, email: [email protected]
Manipulation of squeezed states through optomechanical interaction
Simona Mosca1, Antonio Borrielli2,3, Iolanda Ricciardi1, Maria Parisi1
Michele Bonaldi2,3, Paolo De Natale4, Francesco Marin5, Maurizio De Rosa1
1
INO–CNR, Istituto Nazionale di Ottica, Sezione di Napoli
Via Campi Flegrei 34, I-80078 Pozzuoli (NA), Italy
2
Institute of Materials for Electronics and Magnetism
Via alla Cascata 56/C, 38123 Trento (TN), Italy
3
INFN Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Trento,
Via alla Cascata 56/C, 38123 Trento (TN), Italy
4
INO–CNR, Istituto Nazionale di Ottica,
Largo Enrico fermi 6, 50125 Firenze FI, Italy
5
Dipartimento di Fisica e Astronomia, Università di Firenze
via Sansone 1, 50019 Sesto F.no (FI), Italy
Quantum optomechanics is an extremely active research area, exploring quantum
mechanics in entirely new ways. The interplay between mechanical and cavity optical
modes gives rise to a variety of effects which, in the quantum regime, can enable the
observation of quantum behaviour of objects many orders of magnitude larger and more
massive than atomic-scale quantum systems. It has been showed that the coupling
induced between light amplitude and phase fluctuations can lead to spectrally tailored
squeezing of classical coherent states of light (ponderomotive squeezing) [1-6]. Our
experiment aims at manipulating and controlling the spectral dependence of the field
quadratures fluctuations of a nonclassical squeezed state of light, by exploiting the
optomechanical interaction. The optomechanical system is a single-ended high-finesse
Fabry-Pérot cavity whose end mirror is a cryogenically cooled mechanical
microresonator. The mirror must have low mechanical (Q-factor ~ 106) and optical
losses (5x104 of finesse when used in cavity). The input squeezed light is generated by a
sub-threshold optical parametric oscillator pumped by the second harmonic of an IR
light at 1064 nm. Optical homodyne tomography will be used for quantum state
analysis.
[1] C. Fabre et al., “Quantum-noise reduction using a cavity with a movable mirror”, Phys. Rev. A 49,
1337 (1994).
[2] S. Mancini and P. Tombesi, “Quantum noise reduction by radiation pressure”, Phys. Rev. A 49, 4055
(1994).
[3] D. W. Brooks et al. “Non-classical light generated by quantum-noise-driven cavity optomechanics”
Nature 488, 476 (2012).
[4] T. P. Purdy et al., “Strong Optomechanical Squeezing of Light”, Phis. Rev. X 3, 031012 (2013).
[5] A. H. Safavi-Naeini et al., “Squeezed light from a silicon micromechanical resonator” Nature 500,
189 (2013).
[6] A. Pontin et al., “Frequency-noise cancellation in optomechanical systems forponderomotive
squeezing” Phys. Rev. A 89, 033810 (2014).
Presenting author: Simona Mosca, email: [email protected].
The MONICA Project: Novel Monitoring of coast and sea enviroment
S. Avino1, M. De Rosa1, G. Gagliardi1, A. Giorgini1, P. Malara1, S. Mosca1, M. Parisi1,
M. Paturzo1, I. Ricciardi1, A. Rocco1, P. Ferraro1, P. De Natale2
1
CNR-INO, , Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
2
CNR-INO, , Largo E. Fermi 6, 50125 Firenze, Italy
The MONICA project was conceived to give a major contribution to prevention and
management of sea and coastal environmental emergencies. In particular, the main goal
of the project was to realize a monitoring network based on fiber optic communication
connecting traditional and innovative sensors. The project findings aim to monitor
emerged and submerged areas in Pozzuoli Gulf, through an early warning system and
manage hydrogeological and volcanic hazard.
We have developed innovative sensors which can be easily connected in complex
structures for geophysical and geochemical parameters monitoring, in particular:
- fiber Bragg grating-based sensors for mechanical strain and acceleration
measurements;
- evanescent wave-based sensors for chemical analysis of liquid samples [1,2];
- 3D digital holographic systems for non-intrusive imaging of aquatic microorganisms
[3,4].
References
[1] S. Avino, C. Richmond, A. Giorgini, P. Malara, R. Zullo, P. De Natale and G. Gagliardi, High
sensitivity ring-down evanescent-wave sensing in fiber resonators, Opt. Lett., 39, 5725, (2014).
[2] S. Avino, A. Giorgini, M. Salza, M. Fabian, G. Gagliardi, P. De Natale, Evanescent-wave comb
spectroscopy of liquids with strongly dispersive optical fiber cavities, Applied Physics Letters, 102,
201116 (2013).
[3] M. Paturzo, A. Finizio, P. Memmolo, R. Puglisi, D. Balduzzi, A. Galli and P. Ferraro, Microscopy
imaging and quantitative phase contrast mapping in turbid microfluidic channels by digital holography,
Lab Chip, 12, 3073 (2012).
[4] V. Bianco, M. Paturzo, A. Finizio, D. Balduzzi, R. Puglisi, A. Galli, P. Ferraro, Clear coherent
imaging in turbid microfluidics by multiple holographic acquisitions, Opt. Lett., 37, 4212, (2012).
Presenting author: Maria Parisi, [email protected].
Comb-assisted Sub-kHz-linewidth Optical Parametric Oscillator for
High-precision Spectroscopy
I. Ricciardi1, S. Mosca1, M. Parisi1, P. Maddaloni1, L. Santamaria1, G. Giusfredi2,
P. De Natale2, and M. De Rosa1
1
CNR-INO, Istituto Nazionale di Ottica, Pozzuoli (NA), Italy
2
CNR-INO, Istituto Nazionale di Ottica, Firenze, Italy
Highly stable and spectrally pure laser sources are crucial for a wide range of
demanding applications, including frequency metrology, precision tests of fundamental
physics, and high-resolution spectroscopy in the mid-infrared region of the
electromagnetic spectrum, where intense ro-vibrational transitions of many molecules
are present [1]. Among the mid-infrared sources, OPOs combine in the same device
unique features, such as high power, single mode emission, tunability and wide spectral
coverage, thus providing their suitability for high-sensitivity spectroscopy[2-4]. A large
number of visible and near infrared lasers have been narrowed down to
sub-Hertz-linewidth and their frequency absolutely stabilized up to the level of the best
optical frequency standards, while sub-kHz narrowing of mid-infrared sources is limited
to a couple of gas lasers and more recently to quantum cascade lasers.
Here, we report on sub-kHz linewidth narrowing of an optical parametric oscillator
(OPO) idler mode [5].
References
[1] P. Maddaloni, M. Bellini, P. De Natale, Laser-Based Measurements for Time & Frequency Domain
Applications, CRC Press, 2013.
[2] M. De Rosa, E. De Tommasi, P. Maddaloni, S. Mosca, I. Ricciardi, A. Rocco, J.-J. Zondy, and P. De
Natale, in Ferroelectric Crystals for Photonic Applications, P. Ferraro, S. Grilli, and P. De Natale, eds.
Springer, Berlin, Heidelberg, 2014.
[3] I. Ricciardi, E. De Tommasi, P. Maddaloni, S. Mosca, A. Rocco, J.-J. Zondy, M. De Rosa, and P. De
Natale, Frequency-comb-referenced singly-resonant OPO for sub-Doppler spectroscopy, Opt. Express 20,
91789186 (2012).
[4] I. Ricciardi, E. De Tommasi, P. Maddaloni, S. Mosca, A. Rocco, J.-J. Zondy, M. De Rosa, and P. De
Natale, A narrow-linewidth optical parametric oscillator for mid-infrared high-resolution spectroscopy,
Mol. Phys. 110, 21032109 (2012).
[5] I. Ricciardi, S. Mosca, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale, and M. De Rosa,
Sub-kilohertz linewidth narrowing of a mid-infrared optical parametric oscillator idler frequency by
direct cavity stabilization, Opt. Let. 40 (20), 2015, 4743-4746.
Presenting author: Iolanda Ricciardi, [email protected]
Direct generation of optical frequency combs in χ(2) nonlinear cavities
M. Parisi1, I. Ricciardi1, S. Mosca1, P. Maddaloni1, L. Santamaria1, T. Hansson2,3,
S. Wabnitz3,1, P. De Natale4, and M. De Rosa1
1
CNR-INO, Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
Department of Applied Physics, Chalmers University of Technology,
SE-41296 Göteborg, Sweden
3
Dipartimento di Ingegneria dell’Informazione, Università di Brescia,
Via Branze 38, 25123 Brescia, Italy
4
CNR-INO, Largo E. Fermi 6, 50125 Firenze, Italy
2
Since they appeared, optical frequency combs had a dramatic impact on the field of
metrology. Nowadays, frequency combs have plenty of other applications, ranging from
synchronization of telecommunications systems to astronomical spectral calibration, or
as spectrometers for biomedical and environmental applications.
We demonstrate direct frequency comb generation in continuously-pumped quadratic
nonlinear crystals placed inside an optical cavity [1]. At the same time, we provide a
frequency-domain theoretical description of the phenomenon, presenting a quantitative
spectral dynamical model and a stability analysis of different cavity field regimes [2].
The proposed model offers a deep physical insight into χ(2) comb dynamics and
interestingly displays a striking analogy with the description of frequency comb
generation in Kerr nonlinear resonators [3-4], suggesting a unified theoretical
framework for the physics of frequency combs.
References
[1] I. Ricciardi, S. Mosca, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale and M. De Rosa,
Frequency comb generation in quadratic nonlinear media, Phys. Rev. A 91, 063839 (2015).
[2] S. Mosca, I. Ricciardi, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale and M. De Rosa, Direct
generation of optical frequency combs in χ(2) nonlinear cavities, arXiv: 1510.08074 [physics.optics]
(2015).
[3] T. J. Kippenberg, R. Holzwarth, and S. A. Diddams, Microresonator-Based Optical Frequency Combs,
Science 332, 555 (2011).
[4] T. Hansson, D. Modotto, and S. Wabnitz, Dynamics of the modulational instability in microresonator
frequency combs, Phys. Rev. A 88, 023819 (2013).
Presenting author: Iolanda Ricciardi, [email protected]
Optical dissection of cardiac electrophysiology
C. Crocini1, M. Scardigli1, R. Coppini2, C. Ferrantini3, P. Yan4, L. Loew4, C. Poggesi3,
E. Cerbai2, F. S. Pavone5,6,1, and L. Sacconi1,6
1
European Laboratory for Non-Linear Spectroscopy (LENS), Florence, Italy.
Division of Pharmacology, Department “NeuroFarBa”, University of Florence,
Florence, Italy
3
Division of Physiology, Department of Experimental and Clinical Medicine,
University of Florence, Florence, Italy
4
R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health
Center, Farmington, Connecticut, United States of America
5
Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
6
National Institute of Optics (INO), National Research Council (CNR), Florence,
Italy.
2
Abstract
Synchronous cardiac contraction is guaranteed by a sophisticated conductive system
that allows the action potential, originated in the pacemaker cells, to rapidly recruit each
cardiac myocyte of the heart. In addition, every cell is activated in its entirety thank to a
complex network of membrane invaginations, named the transverse-axial tubular
system or T-tubules. T-tubules allow the electrical trigger to reach every portion of
cardiac cells and eventually producing a coherent contraction of the cell. Both these two
systems are needed to maintain the proper function of the heart. Here, we show how
advanced optical microscopy techniques can be used for exploring the role of T-tubules
in cardiac physiology and pathology and unveiling the basis of arrhythmia by optically
manipulating the cardiac electrical activity in whole hearts.
Presenting author: Leonardo Sacconi, National Institute of Optics (INO-CNR) c/o LENS - European
Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (FI), Italy, tel. 055
4572451, [email protected].
Skin microbiota monitoring by Nanowire MOS Sensors.
V. Sberveglieri1 , E. Núñez Carmona 1,2, A. Ponzoni 1, E. Comini 1,3
V. Galstyan 1, D. Zappa 1,3, A. Pulvirenti 1,2.
1
CNR-INO Sensor Lab, Via Valotti 9 – 25133 Brescia Via Branze 45, Italy.
2
University of Modena and Reggio Emilia, Department of Life Science, 42124 Reggio
Emilia, Italy.
3
University of Brescia, Department of Information Engineering, Via Branze 45, 25123
Brescia, Italy.
Abstract
The human body can be considered as a super organism since for each one of the
animal cells, 10 microorganisms are living in the skin and the mucosa. The normal
microbiota (NM) is composed by fungi, yeast and in a major part for bacteria and its
quantitative and qualitative composition may change due to external factors or different
physiological condition [1]. The microbial antagonism is a property, which enables one
microorganism to kill, or inhibit the growth of a different one.
Metal Oxide Nanowires were synthetized using a simple and scalable
evaporation-condensation technique, directly on final transducers used for the
fabrication of the sensing devices [2]. S3 device equipped with nanowire (Nw)
technology is created for the analysis of the headspace. The features that S3 possess
make possible to reveal the presence of the microorganisms trough the detection of the
organic volatile compounds (VOCs) produced during their metabolic activities. In some
cases, individualizing species of the same group of microorganisms. The aim of this
work is to set up a new approach based on the collaboration between Nw technology
and classical techniques, to establish a new fouling to monitor the development of NM
of the skin. Nw technology has already proven its ability to identify different single
microorganism and follow up their development inside a microbial cultures [3]. The
achieved results (Fig.1) strongly support the ability of the device to discriminate
between the three different blends, follow the different stages of the culture
development, and the change of the microbial composition of the blends.
Fig. 1 . PCA Score plot of the 4 samples kind in the first 20 h of analysis.
References
[1] E. A. Grice, H. H. Kong, G. Renaud, A. C. Young, G G. Bouffard, R. W. Blakesley, T. G. Wolfsberg, M. L. Turner, J. A. Segre1, A
diversity profile of the human skin microbiota, Genome Research 18 (2008)1043–1050.
[2] G. Sberveglieri, I. Concina, E. Comini, M. Falasconi, M. Ferroni, V. Sberveglieri, Synthesis and integration of tin oxide
nanowires into an electronic nose, Vacuum 86 (2012) 532-535.
[3] V. Sberveglieri, E. Núñez Carmona,, A. Pulvirenti, Detection of microorganisms in water and different food matrixby by
Electronic Nose, Sensing Technology: Current Status and Future Trends III, (2015) 243-258.
Presenting author: Vardan Galstyan, Department of Information Engineering, Via Branze 45, 25123 Brescia, Italy.
Photonic necklace states in 2d and integrated single quantum
emitters
F. Sgrignuoli1,2, G. Mazzamuto2,3, S. Checcucci 2,3, P. Lombardi 2,3, S. Rizvi 2,3, N.
Caselli1,3, F. Intonti1,3, M.Agio 4,5, M. Gurioli1,3, F.S. Cataliotti1,3,4, C. Toninelli2,3,4
1
Dipartimento di Fisica, Università di Firenze, Via Sansone 1,I-5001 Sesto F.no, Italy
2
CNR-INO, Istituto Nazionale di Ottica, Via Carrara 1, 50019 Sesto F.no, Italy
3
LENS e Università di Firenze, Via Carrara 1, 50019 Sesto F.no, Italy
4
QSTAR, Largo Fermi 2, I-50125 Firenze, Italy
5
Nano-optics Laboratory, University of Siegen, Walter-Flex Strasse 3, 57072 Siegen,
Germany
Abstract
Nowadays, the integration of a single quantum emitter, i.e single photon source,
with different photonic architectures poses a great research challenge. Indeed, this
interconnection can be considered as the heart of various cutting edge research topics,
including cryptography, cavity quantum electrodynamics, and quantum information
networks [1].
In this work, I will first discuss the role of disorder in 2D photonic structures,
constituting a relevant platform for quantum emitter integration and then present results
on the efficient beaming of single molecule by means of robust planar optical antennas.
The term “disorder” in photonic tends to carry a negative stigma. However, it
represents also the common denominator of a plethora of phenomena, characterized by
a multiple-scattering description. In particular, we focus on the interplay between order
and disorder in photonic structures to allow an efficient coupling between otherwise
confined modes. These coupled states, i.e. necklace state, are responsible for transport
in otherwise localizing systems. However, necklace state statistical occurrence in
dimensions higher than one is hard to measure, because of the lack of a decisive
signature. We provide a method to fill this gap. By analysing the phase spatial
probability distribution of the electromagnetic field (PSPD), which is nowadays
obtainable by means of near-field optical microscope measurements, we observe a
bimodal signature of the equivalent necklace states in 2D. We exploit the analogy to a
system of coupled photonic crystal cavities in order to closely relate the double peak in
the PSPD to the coupling between resonant modes. In particular, we study the mode
profile as a function of relative mode detuning and coupling strength [2]. These results
are crucial in enabling a statistical approach, hence to allow controlling composite-mode
effects in random systems.
For the second purpose, we use a multi-layered device with an active layer DBTbased. From a photonic point of view, light detection form a sub-wavelength source can
be regarded as an antenna problem, where the light emitted by a Hertzian dipole has to
be efficiently collected by a receiver. The goal is that of engineering the electromagnetic
environment around the emitter to reduce the directivity of the receiver, i.e. to reduce
the numerical aperture of the collection optics. Both numerical and experimental results
show that the modification of the radiation pattern of a sub-wavelength emitter channels
its emission into a narrow cone, opening a new route into the single-emission detection
scenario.
References
[1] B. Lounis, and M.Orrit, Single-photon sources, Rep. Prog. Phys.,68 (2010) 1129-1179.
[2] F.Sgrignuoli, et al, Necklace State Hallmark in disordered 2D photonic crystals, ACS-Photonics,
(2015) doi: 10.1021/acsphotonics.5b00422.
Presenting author: Fabrizio Sgrignuoli, Via Nello Carrara1, I50019, Sesto F.no, 055-4572389,
[email protected].
Finite element modeling of strained-Si waveguide for mid-IR
upconversion
I. López1,2, M. Siciliani de Cumis2,3, D. Mazzotti2.3, P. Cancio Pastor2,3, P. De Natale2,3,
M. Ghulinyan4, F. Ramiro Manzano5, L. Pavesi5
1
Istituto Nazionale di Ottica (INO) - CNR, BEC Center, Povo TN, Italy
2
Istituto Nazionale di Ottica (INO) - CNR, Sesto Fiorentino FI, Italy
3
European Laboratory for Non-linear Spectroscopy (LENS), Sesto Fiorentino FI, Italy
4
Fondazione Bruno Kessler (FBK), Povo TN, Italy
5
Università di Trento, Povo TN, Italy
Abstract
Silicon photonic devices are of paramount importance in the development of future
quantum technologies based on photon-properties manipulation. Strained-silicon
waveguides are a promising tool for mid-IR light detection based on upconversion of
light to the near IR [1-3].
We present a Finite Element Modeling of strained-silicon waveguides realized in
collaboration with Università di Trento and Fondazione Bruno Kessler (FBK).
Analysis and numerical simulations are used to investigate and characterize the
waveguides designed and fabricated for nonlinear photonics. The in-deep study led us to
know about the waveguiding behaviour according to different parameters, such as
doping, waveguide dimensions, laser wavelength, light polarization and temperature.
This first step allowed us to predict the possible behaviour of a Si3N4/Si/SiO2 slab
waveguide, in particular, the second-order nonlinear optical susceptibility, χ (2), in order
to realize a sum-frequency generation process [4].
After the simulation we are going to perform the experiment, by injecting into the
waveguide two laser beams at different wavelengths: a fs-pulsed laser beam
(λ1=1.55 µm) and a CW laser (λ2=2.64 µm). The generation of a third signal at
λ3=0.98 µm is expected and it will be detected at the waveguide output. The complete
study of strained-silicon waveguides is expected to provide us a wide range of photonic
devices for the new generation of telecommunications.
References
[1] L. Pavesi and D. Lockwood, Silicon photonics I, (Topics in Appl. Phys. 94, Spinger, 2004).
[2] D. Lockwood and L. Pavesi, Silicon photonics II, (Topics in Appl. Phys. 119, Spinger, 2011).
[3] M. Cazzanelli et al., Second-harmonic generation in silicon waveguides strained by silicon nitride,
Nat. Mater., 11 (2012) 148-154.
[4] I. Avrustky and R. Sorel, Phase-matched sum frequency generation in strained silicon waveguides
using their second-order nonlinear optical susceptibility, Opt. Express, 19 (2011) 21707-21716.
Presenting author: M. Siciliani de Cumis, c/o LENS, Via Carrara 1, 50019 Sesto Fiorentino FI. Tel.: +39
-055-457-2292/2222, e-mail: [email protected]
Modulation instabilities, temporal patterns and frequency comb
generation in quadratic nonlinear resonators
1
F. Leo1, T. Hansson2,3, I. Ricciardi4, M. De Rosa4, S. Coen1, S. Wabnitz3,4, and M.
Erkintalo1,
The Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, The
University of Auckland, Auckland 1142, New Zealand
2
Department of Applied Physics, Chalmers University of Technology,
SE-41296 Göteborg, Sweden
3
Dipartimento di Ingegneria dell’Informazione, Università di Brescia,
Via Branze 38, 25123 Brescia, Italy
4
CNR-INO, Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
We derive time-domain, mean-field equations to model the full temporal and spectral
dynamics of light in both singly resonant and doubly resonant cavity-enhanced
second-harmonic generation (SHG) systems. We show that the temporal walk-off
between the fundamental and the second-harmonic fields plays a decisive role under
realistic conditions, giving rise to a rich, previously unidentified nonlinear behaviour.
Through linear stability analysis and numerical simulations, we discover a new kind of
quadratic modulation instability (MI) which leads to the formation of optical frequency
combs and associated time-domain dissipative structures [1]. Our numerical simulations
show excellent agreement with recent experimental observations of frequency combs in
quadratic nonlinear media [2].
In addition to unveiling a new, experimentally accessible regime of nonlinear
dynamics, our work enables the predictive modeling of frequency comb generation in
cavity-enhanced SHG systems. For example, in the yet experimentally unexplored
doubly resonant cavity SHG case, our numerical simulations reveal that, for realistically
large walk-offs, the MI may give rise to temporal patterns and solitary waves that
correspond to coherent optical frequency combs.
Finally, we performed a numerical study by means of the generalized nonlinear
envelope equation, including quadratic and cubic nonlinearities, of the process of
frequency comb generation in the visible, near and mid-infrared spectral regions from a
continuous-wave pumped periodically poled lithium niobate microring resonator via the
interplay of SHG, optical parametric oscillation and sum-frequency generation.
References
[1] F. Leo, T. Hansson, I. Ricciardi, M. De Rosa, S. Coen, S. Wabnitz, and M. Erkintalo,
"Walk-off-induced modulation instability, temporal pattern formation, and frequency comb generation in
cavity-enhanced second-harmonic generation," arXiv:1510.04261 [physics.optics].
[2] I. Ricciardi, S. Mosca, M. Parisi, P. Maddaloni, L. Santamaria, P. De Natale and M. De Rosa,
Frequency comb generation in quadratic nonlinear media, Phys. Rev. A 91, 063839 (2015).
Presenting author: Stefan Wabnitz, Dipartimento di Ingegneria dell’Informazione, Università di Brescia,
Via Branze 38, 25123 Brescia, +030-33715846, +030-380014, [email protected].
Volumetrically nanostructured reconfigurable metasurfaces
and integrated photonic components
1
S. Zanotto1, S. Nocentini2, C. Parmeggiani1, and D. S. Wiersma2
INO-CNR,UOS LENS,Via Nello Carrara 1, 50019 Sesto Fiorentino (FI)
2
LENS - Laboratorio Europeo di Spettroscopie Non-Lineari,
Università degli Studi di Firenze, 50019 Sesto Fiorentino (FI)
Abstract
Photonics is known to be one of the key enabling technology of the last decades. Far
from being an exhausted field of study, however, photonics is still believed to reserve
major breakthroughs especially in connection with telecommunications, biomedical
research, and energetics.
Photonic devices strongly rely on material science. Among the different materials which
deserve an interest, polymers are well known for their good optical properties, their
biocompatibility and the possibility to be nanostructure them. By nanostructuration, the
interaction of light with materials is forced on the wavelength or subwavelength scale,
and devices like photonic crystals and metamaterials can be exploited for components of
telecommunication systems, for biomedical essay techniques, or for efficient solar cells
[1 - 3]. Most of the devices proposed up to date, however, are static, i.e., they cannot be
tuned to the desired working point. For many applications, instead, a reversible and
stable tuning of the optical properties is a desirable attribute and can introduce a higher
level of functionality.
Hence, the development of photonic structures and
metamaterials where some units can be dynamically reconfigured would be a major
result, opening up new avenues in the technology of light.
Our research plan is to merge the concepts of responsivity and volumetric
nanostructuration. In detail, we will combine the reconfigurability of functionalized
polymers and the possibility to create volumetrically, i.e., three-dimensionally
nanostructured devices, though a direct laser writing (DLW) lithographic technique [4,
5]. The union of these two key features is expected to deliver a new class of photonic
devices such as bistable filters and chirality-sensitive optical surfaces.
References
[1] N. Yu and Federico Capasso, “Flat Optics with Designer Metasurfaces” Nature Materials 13,
139 (2014)
[2] A. Moreau et al., “Controlled-Reflectance Surfaces with Film-Coupled Colloidal
Nanoantennas”, Nature 492, 86 (2012)
[3] J. D. Joannopoulos, P. R. Villeneuve, and S. Fan. "Photonic crystals: putting a new twist on
light." Nature 386, 143 (1997)
[4] M. M. Hossain and M. Gu, “Fabrication Methods of 3D Periodic Metallic
Nano/microstructures for Photonics Applications”, Laser and Photonics Reviews 8, 233
(2014)
[5] A. Flatae et al. “Optically controlled elastic cavities.” Light: Science & Applications 4, 282
(2015)
Presenting author: Simone Zanotto,Via Nello Carrara 1, 50019 Sesto Fiorentino (FI), 055 4572524,
[email protected].
Optical measurements of a sol gel transition
R. Zullo1, P. Malara1, L. Verdolotti2, M. Lavorgna2, G. Filippone3, A. Giorgini1, S. Avino1, G.
Gagliardi1
1
CNR-Istituto Nazionale di Ottica (INO), via Campi Flegrei 34, Complesso “A. Olivetti”, 80078 Pozzuoli
(Napoli), Italy
2
Institute of Polymers, Composites and Biomaterials (IPCB-CNR), P.le E. Fermi, 1-Loc. Granatello,
80055 Portici (Napoli), Italy
3
Dipartimento di Ingegneria chimica, dei materiali e della produzione industriale (DICMaPI), P.le
Tecchio 80, 80125 (Napoli), Italy
Abstract
The sol-gel is a transition where the colloidal suspension of solid particles in a liquid
(sol) evolves toward the formation of a gel-like system with properties between liquid
and solid through a continuously extending polymer network. Experimental rheology,
combined with theories of percolation and branching [1, 2] is widely used to determine
the features of this liquid-solid transition [3, 4, 5]. However, in several systems (such as
gels starting from inorganic solutions of sodium silicate and catalyzed by solution of
bicarbonate of sodium) the gel transition point cannot be well determined with
rheological tests and application of classical theory. The viscosity of the sol state is in
fact typically below the measurement range of traditional rheometers. Furthermore, the
rheological tests actively stress the material and can influence the polymer network
during gelation.
An optical interrogation approach of the sol-gel transitions is presented in this work. An
optical fiber with a Fiber Bragg grating (FBG) written in its core is tightly stretched in
the sol liquid phase. Upon a small, instantaneous mechanical stimulation, the fiber
undergoes a series of small oscillations. The instantaneus strain of the FBG, measured
from its reflectivity, tracks these oscillations, allowing monitor their damping time. The
evolution chart of the damping time directly maps the sol-gel transition. The proposed
method overcomes the limited measurement range of traditional rheometers and allows
to follow the polymer network development with a minimal influence on the system.
References
[1] C. J. Brinker, G. W Scherer, The phisics and chemistry of sol-gel processing, Academic Press Inc.
[2] D. Stauffer, A. Aharony An Introduction to Percolation Theory, Taylor & Francio, London (1992).
[3] M. E. de Rosa, M. Mours, H. H. Winter, The gel point as a reference state: a simple kinetic model for
crosslinking polybutadiene via hydrosilation, Polymer Gels and Networks, 5 (1997) 69-94.
[4] S. Mortimer, A. J. Ryan, and J. L. Stanford, Rheological Behavior and Gel-Point Determination for a
Model Lewis Acid-Initiated Chain Growth Epoxy Resin, Macromolecules, 34 (2001) 2973-2980.
[5] H. H. Winter and F. Chambon, Analysis of Linear Viscoelasticity of a Crosslinking Polymer at the Gel
Point, J. Rheol. 1986, 30, 367.