(Waveguide theory and) photonic circuit design

2572-2
Winter College on Optics: Fundamentals of Photonics - Theory,
Devices and Applications
10 - 21 February 2014
(Waveguide theory and) photonic circuit design
A. Melloni
Dip. Elettronica, Informazione e Bioingegneria
Politecnico di Milano
Italy
Winter College on Optics: Fundamentals of Photonics Theory, Devices and Applications
(Waveguide theory and) photonic
circuit design
A. Melloni
Dip. Elettronica, Informazione e Bioingegneria
Politecnico di Milano, Italy
7th Optoelectronics & Photonics Winter School: Physics and Applications of Optical Resonators – A. Melloni, Politecnico di Milano
Waveguide theory and photonic circuit design
- Waveguides (no theory…)
- The role of index contrast in waveguides (survey of technologies, type of
waveguides, index contrast…)
- Bends and advanced topics on bends (the matched bend,...)
- The dark side of integrated optical waveguides (backscatter, xtalk, losses,
spurious modes, the (ng-neff) role….)
- An excursus on ring resonators: history, spectral characteristics,
applications, ...
- Circuits: MZ, rings, higher order filters, delay lines, …
- The circuit approach (building Blocks, Circuit simulators and few slides on
Aspic, our circuit simulator that will be used at the end of the course for
hands-on session).
- The structure of generic foundries and available generic foundries
7th Optoelectronics & Photonics Winter School: Physics and Applications of Optical Resonators – A. Melloni, Politecnico di Milano
Let’s combine rings
A. Melloni
from Ring to Rings…
A. Yariv
Caltech
1999
Microwave
C. Madsen
Bell Labs
1999
DSP
R. Orta
Politecnico Torino
1999
DSP
A. Melloni
Politecnico Milano
2002
Microwave
V. Van
Maryland Univ.
2006
Electronic/Microwave
Books from I. Chremmos, O. Schwelb, D.G. Rabus, J. Hebneer, ….
ORES School, Levico, 2013
A. Melloni
from Ring to Rings…
Parallel coupled bandstop filter
Directly coupled bandpass filter (CROW)
Ring-loaded Mach-Zehnder filter
ORES School, Levico, 2013
A. Melloni
Ring loaded Mach-Zehnder
APF allows to shape
the phase response
2(N+1)
1()
2()
ORES School, Levico, 2013
A. Melloni
FSR
2N
Tunable bandwidth filter

kc

Lr
kr
Lr
kr
kc
Bandwidth tunability is obtained by varying 
FSR = 200 GHz
B = 23 GHz … 175 GHz
IL < 0.6 dB
ER > -18 dB
ORES School, Levico, 2013
A. Melloni
Coupled resonators
ORES School, Levico, 2013
A. Melloni
8
Direct coupled cavities vs cascaded cavities
Cascaded cavities
(SCISSOR)
Direct coupled cavities
(CROW)
-5
0
1
Transmission [dB]
Transmission [dB]
0
-10
-15
2
5
-20
-25
-1
-0.5
0
0.5
Frequency
ORES School, Levico, 2013
A. Melloni
1
-5
1
-10
-15
2
-20
-25
-1
-0.5
5
0
Frequency
0.5
1
Identical cavities ?
0
1 cavity
Transmission [dB]
-1
K=0.01
-2
1st order cavity d=/2
-3
B1 cavity=1.2 THz
B=1.2THz
-4
-5
-1500
-1000
-500
0
500
Frequency [GHz]
BCROW=22.5 THz
1000
1500
100 cavities
0
0
-10
-10
Transmission [dB]
Transmission [dB]
10 cavities
-20
-30
-50
-1.5
-1
-0.5
0
0.5
Frequency [GHz]
ORES School, Levico, 2013
-30
B=22THz
-40
B=22THz
-40
-20
1
A. Melloni
1.5
x 10
4
-50
-1.5
-1
-0.5
0
0.5
Frequency [GHz]
1
1.5
4
x 10
CROW impedance matching
/4
-14 dB
ZCROW  2n g ( )
0 dB
|H(f)|2 [dB]
CROW
ZW  n eff
Quarter-wave
matching
neff
Frequency [GHz]
( / 4 )
 n eff 2n g
No impedance
matching
11
ORES School, Levico, 2013
A. Melloni
Impedance Matching (Apodization)
...
ZCROW  2n g ( )
ZW  n eff
Quarter-wave
matching
neff
( / 4 )
 n eff 2n g
No impedance
matching
ORES School, Levico, 2013
A. Melloni
Coupled ring resonators
THROUGH
K0
IN
DROP
f0
K1
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f0
K2
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f0
f0
K3
f0
K2
K1
f0
K0
Progress in tuneable ringring-CROW
2009
2007
2008
2009
2010
56 μm
N x 40 μm
F. Morichetti et al., The first decade of coupled resonator optical waveguides: bringing slow
light to applications.
Laser & Photonics Reviews, 6: 74–96 (2012)
ORES School, Levico, 2013
A. Melloni
8-rings Bandpass filters in SOI
Intensity [dBm]
Return loss: -15 dB; IL 0.5 dB; In-band ripple <0.2 dB; Off-band rejection >50 dB
Wavelength [nm]
A. Melloni
8-rings Bandpass filters in SOI
-2
10
Waveguide
λ=1536.27 nm
λ=1550.42 nm
-3
10
λ=1564.75 nm
-4
BER
10
-5
10
-6
10
-7
10
-8
10
-9
10
-10
10
-11
10
-12
10
6
8
10
12
14
16
18
OSNR
over 0.2 [nm]
nm
Wavelength
A. Melloni
20
22
Thermal tuning
NiCr
Spin‐on glass
SiO2
Thermal crosstalk
hot ring
Au
wh
h
Si
w
=2.5 nm 28° C
Si
0.7° C
-20
Transmission [dB]
cold ring
7 m
=0.06 nm
8 rings
-30
7 rings
-40
6 rings
5 rings
-50
4 rings
-60
3 rings
-70
1556
1558
ORES School, Levico, 2013
1560
1562
Wavelength [nm]
A. Melloni
1564
1566
Tunable Delay lines
A. Melloni
On-Chip Tunable delay… not an easy task !!!
out
Electronic
Microwave
Photonics
- let photons run around (coil of fiber)
ORES School, Levico, 2013
– slow down photons
A. Melloni
Recirculating buffer
Discrete delay line, Packet(s) delay and Buffer
Technologies: 2007 Glass for the spire + InP for the switch
2010 All Silicon (15 dB/ns)
Trade off between waveguide attenuation and switch ER (limit)
Spires
Switches
Courtesy of John Bowers, University
of California, Santa Barbara
ORES School, Levico, 2013
A. Melloni
INTEL 2010
Slow down photons
Transmission
c
velocity 
group refractive index
ng of the material: Atomic resonances, band edge, EIT, CPO,…
ng of the circuit: Resonators, Bragg Gratings, Photonic
Crystals, Brillouin and Raman,…
ORES School, Levico, 2013
A. Melloni
Slow down photons
ORES School, Levico, 2013
A. Melloni
Tunable Delay lines
1 byte continuously tuneable delay at 10 and 100 Gbit/s demonstrated
OUT
open rings
IN
λr = λin
closed rings
λr ≠ λin
F. Morichetti et al., Optics Express, Vol. 15, 25, December 2007
A. Canciamilla et al., Journal of Optics, IOP, 2010
A. Melloni et al., IEEE Photonics Journal, vol. 1, no. 4, 2010
ORES School, Levico, 2013
A. Melloni
The CROW in reflection
Out
Locked rings
(off-resonance)
in
In
0.8
350
In
300
Minimum delay
0.6
0.4
0.2
Delay [ps]
Intensity
1
r ≠in
200
150
100
50
0
-200 -100
250
0
100
200
Time [ps]
ORES School, Levico, 2013
300
A. Melloni
400
500
0
-20
-15
-10
-5
0
5
Frequency [GHz]
10
Frequency [GHz]
15
20
The CROW in reflection
Out
Locked rings
(off-resonance)
M = 2
in
In
Open rings
(on-resonance)
0.8
0
In
2
Delay [ps]
Intensity
1
r ≠in
0.6
0.4
0.2
0
-200 -100
0
100
200
300
Time [ps]
ORES School, Levico, 2013
A. Melloni
400
500
Frequency [GHz]
R-CROW: a reconfigurable delay line
Out
M = 4
Locked rings
(off-resonance)
in
In
Open rings
(on-resonance)
0.8
0
In
2
0.6
Delay [ps]
Intensity
1
r ≠in
4
0.4
0.2
0
-200 -100
0
100
200
Time [ps]
300
400
500
F. Morichetti et al., Optics Express, no. 25, Dec. 2007
ORES School, Levico, 2013
A. Melloni
Frequency [GHz]
R-CROW continuous tuning
ORES School, Levico, 2013
A. Melloni
Data transmission at 10 Gbit/s
100 ps
Intensity modulation
OOK NRZ @ 10 Gbit/s
In
Reconfiguration
- hitless
- time 100 s
- power 5 mW
ORES School, Levico, 2013
Out
A. Melloni
Tuneable pulse delay @100Gbit/s
B = 87 GHz
10 ps
In
τ
Out
Normalized intensity
Fractional delay = 7.5 ps/RR
1
(0)
0.8
Storage efficiency
0.66 bit/RR
89 ps (8 bits)
0.6
9 ps
(4)
0.4
(8)
0.2
Fractional loss
≈ 1.1 dB/bit
(12)
11 ps
0
0
20
ORES School, Levico, 2013
40
60
Delay [ps]
A. Melloni
80
100
120
Pulse Broadening (1 byte)
≈ 20%
ORES School, Levico, 2013
A. Melloni
High level circuit design
Final User: PICs design at a circuit level using a selected set of elementary functional elements (BBs), according to well defined rules (DKs)
materials
Builiding
Blocks
technol.
Design kits
waveguides
Generic
Foundries
devices
circuits
packaging
modules
Final Users
ORES School, Levico, 2013
A. Melloni
systems
Modelling of photonic Building Blocks
  E   jB
EM analysis
  H  jD  J
B  H
 D  
Numerical simulations
BB model
S
Characterization
3,53
Simulation
group index
3,52
Higher order mode
exp
3,51
3,5
TE
TE
3,49
TM
TM
3,48
3,47
fundamental mode
3,46
1
2
width [um]
ORES School, Levico, 2013
3
4
A. Melloni
Circuit approach
(high abstraction level) • realistic model • no information on geometry & materials • access only to input/output port waves
• very fast, suitable for large circuits
BBs of the SAPPHIRE platform
Straight & bent waveguides
Waveguide crossing
Ring resonators
Directional couplers
Grating assisted coupler (GAC)
Heaters
Bragg gratings
ORES School, Levico, 2013
In/Out mode adapter
A. Melloni
BBs of the SAPPHIRE platform
Straight & bent waveguides
Waveguide crossing
Ring resonators
Grating assisted coupler (GAC)
Directional couplers
Heaters
Bragg gratings
In/Out mode adapter
ORES School, Levico, 2013
A. Melloni
Design kits
BB
,
model
tB
K
Lc
tX
Design rules
‐ BB connections ‐ validity range of the model
‐ layout constraints
‐ quality assessment
‐…
Analytical model
(S matrix) Circuit parameters & variables
Mask layout
ORES School, Levico, 2013
A. Melloni
SAPPHIRE design manual
Release 1 (July 2012)
Libraries for ASPICTM simulator
SAPPHIRE BBs
www.aspicdesign.com
Play with realistic BB
1600 BBs; 100 lambda points  1 min
Phoenix
Direct exportation of the mask layout
ORES School, Levico, 2013
A. Melloni
ORES School, Levico, 2013
www.phoenixbv.com
www.aspicdesign.com
CITCUIT SIMULATOR
A. Melloni