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Optical Integrated Devices in Silicon On Insulator
for VLSI Photonics
Design, Modelling, Fabrication & Characterization
Piero Orlandi 1
Circuit-Based Approach
•Reduced Design time •Transparent Technology •Shared Access
Classical Optical Design
•All level knowledge •Slow Process •Not suitable for high complexity devices 2
Possible Approaches
Outline •Introduction on SOI Platform and Motivations •Classical Optical Design
•Grating Assisted Coupler (GAC) •GAC-based Microring
•Circuit-Based Approach •Reconfigurable Bandpass Filter •Working principles •Experimental Results
•Conclusions 3
Introduction
On the same chip with electronics: •Inter & Intra chip Interconnection •Transmit receive & process of high data rates signals
Photonic Integrated Circuits
Luxtera 4x10Gb/s WDM Transceivers, 2008 Lee at al., JSTQE,16(1),2010
•High Bandwidth •Low Power Consumption
MOTIVATIONS
SCOPE
NEEDS
Technological Platform: •Very Large Scale Integration (VLSI) •CMOS Compatible
3D Chip multiprocessor Scheme
4
Introduction
•Submicrometre Waveguide •Micrometre Bend Radius •Low Losses
Silicon On Insulator (SOI) Platform
•Very Large Scale Integration (VLSI) 3μm
500nm •CMOS Compatible
•Integration with electronics •Theoretical low cost •Needs for a shared platform
•PhD Work
•Passive devices for routing & add-drop functionality •Reconfigurable Devices 5
Classical Optical Design
Grating Assisted Couplers (GAC) & GAC-based microring resonator
6
100
150
200
250
1 1.5 2 2.5 3
200nm
220nm
240nm
Gap
Structure & Functionality
3d
B B
and
wid
th [
GH
z] Exchange Bandwidth
Grating Assisted Coupler (GAC)
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RD
RX
TX
TD
No
rmal
ized
Inte
nsi
ty
Wavelength [nm]
10/15 8/10 4/6 Perturbation Amplitude [nm]
Experiment vs. Modelling
8 30 15
GAC Based Microring Resonator
Free Spectral Range (FSR) is a Limit!
Ring Resonator
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FSR
Wavelength [nm]
No
rmal
ized
Inte
nsi
ty
Trough=λ1, λm, λ3, …, λN IN=λ1, λ2, λ3, …, λN
Drop= λ2
Add= λm
Trough Drop
Wavelength [nm]
No
rmal
ized
Inte
nsi
ty
Resonance over limited bandwidth
Useful for single wavelength/channel extraction in WDM, Sensor application
GAC Based Microring Resonator
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Idea
GAC Based Microring Resonator Experimental Result
10
Inte
nsi
ty [
a.u
.]
Wavelength [nm]
GAC Based Microring Resonator In
ten
sity
[a.
u.]
Wavelength [nm]
Inte
nsi
ty [
a.u
.]
Wavelength [nm]
Inte
nsi
ty [
a.u
.]
Wavelength [nm] 11
Circuit-Based Approach
Reconfigurable Bandpass Filters Working Principles
Experimental Results (Static & BER)
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PIN
PT
PC
Variable Bandwidth Filter -φr
Kc Kc
Lr Lr Kr Kr PT
PC ΔL= Lr
φr
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Working Principles Optical Filters
LU Kr
φr
PIN PR
k
c
k
c
ULL
L
PIN
MACH-ZEHNDER INTERFEROMETER
RING RESONATOR
Discrete delayed (T) sum of the signal
ULT
Z-Transform Description
ULjez
1
DSP APPROACH
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Periodic Frequency Response
Inte
nsi
ty [
a.u
]
Inte
nsi
ty [
a.u
]
Wavelength [nm] Wavelength [nm]
PT
PC
PT
PC
PR
Working Principles
III Order Butterworth Filter
Maximally Flat Filter Response
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FSRB dB
9/8rK 2/1cK
Power Coupling Coefficients
Symmetric Interleaver [Literature]
NO Bandwidth Tunability
/2
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Inte
nsi
ty [
dB
]
Wavelength [nm]
Working Principles
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FSRB dB =π/2
3/2rK 2/1cK
Power Coupling Coefficients
Symmetric Interleaver [Our Work]
NOW Bandwidth Tunability
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III Order Butterworth Filter
Maximally Flat Filter Response
Inte
nsi
ty [
dB
]
Wavelength [nm]
2
r
23
FSRB dB
3
2 r
3
23
FSRB dB 4
33
FSRB dB
4
3 r
Working Principles Device Simulations
Phase Shift -> Bandwidth Reduction -> Lower Extinction Ratio
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Wavelength [nm] Wavelength [nm] Wavelength [nm]
Inte
nsi
ty [
dB
]
Inte
nsi
ty [
dB
]
Inte
nsi
ty [
dB
]
Fabricated Couplers
Circuit-Based Approach Physical Structure Design
Suitable Parameters
Chosen
18
Fabricated Bends
Couplers Look Up Table
Bends Look Up Table
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NiCr
Ti + Au
Optimized for Tuning
Circuit-Based Approach Physical Structure Design: Heater
Cross Section Scheme Device Top view
Experimental Results Bandwidth Variation
POWER CONSUMPTION
Mean = 28.12mW Std Dev = 0.14mW
170GHz
23GHz
FSR = 200GHz
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3d
B B
and
wid
th [
GH
z]
PR1 – PR2 [mW]
Experimental Results Bandwidth Variation FSR = 200GHz
PT
PC Bandwidth (BW) 170GHz ÷ 23GHz
Always < -16dB 170<BW<40GHz < -18dB
Extinction Ratio (ER)
at Minimum BW 0.6dB
Insertion Loss (IL)
No
rmal
ize
d In
ten
sity
[d
B]
No
rmal
ized
Inte
nsi
ty [
dB
]
Wavelength [nm]
Wavelength [nm] 21
-20 0 20-100
-50
0
50
100
P [mW]
f [G
Hz]
Measurements
Linear Fitting
GHz
mW
f
P3.0
Experimental Results Central Wavelength Variation FSR = 200GHz
Shifted 3dB Bandwidth=FSR/5=40GHz
mW
FSR
P
f017.0
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Experimental Results Experiment vs. Design FSR = 200GHz
Good Agreement! The approach Works
DESIGN EXP. REL. ERROR
FSR 200GHz 198GHz 1%
Minimum T Bandwidth
19GHz
23.1GHz
2%
Minimum C Bandwidth
19GHz
22.4GHz
1.7%
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-14 -12 -10 -8 -6 -4 -2
2
3
4
5
6
7
8
9
10
Pr [dBm]
-log(B
ER
)
OSNR=13dB
OSNR=16dB
OSNR=23dB
B3dB
=170GHz
B3dB
=50GHz
B3dB
=23GHz
OSNR = 23dB No effect on the signal at different Bandwidth
OSNR = 16dB BER = 10-4: 0.5dB Pr gain
BER = 10-9: 0dB Pr gain
OSNR = 13dB BER = 10-4: 1.25dB Pr gain
No variation between 50 and 23 GHz
Experimental Results BER vs. Filter Bandwidth [ASE Noise] FSR = 200GHz
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CONCLUSIONS •Modelling & technological experience has given good results •Designed and realized a reconfigurable device of higher complexity •First demonstration of the circuit based approach •The presented work is the base for the third year activity => Building Block Optimization and Development
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PROJECT SAPPHIRE Shared Access Platform to PHotonic Integrated REsources
Unità Coinvolte:
Fonderia:
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Conference Paper: P.Orlandi, M.Gnan, A.Samarelli, G.Bellanca, A.Melloni, R.M. de La Rue, M.Sorel,”Modeling of Racetrack Resonator with Grating Assisted Coupling”, XVIIIth International Workshop on Optical Waveguide Theory and Numerical Modelling (OWTNM‘10), , 9-10 April 2010, Cambridge, United Kingdom. A. Samarelli, P. Orlandi, M. Gnan, M. Sorel, R.M. De La Rue, A. Melloni, P.Bassi, "Grating Assisted Coupling in Microring Resonators", 15th European Conference of Integrated Optics (ECIO'10), 7- 9 April 2010, Cambridge, United Kingdom, 2010 M. Gnan, P. Orlandi, A. Samarelli, G. Bellanca, A. Melloni, R.M. De La Rue, M. Sorel, P. Bassi, "Accoppiatori Assistiti da Reticolo Associati a Risuonatori ad Anello", XVIII Riunione Nazionale di Elettromagnetismo, Benevento, Italy, September 6-10, 2010. P.Velha, P.Orlandi, A. Samarelli, M.J. Strain, R.M. De La Rue, M. Sorel, P. Bassi,”Microring resonator with wavelength selective coupling in SOI”, The 8th International Conference on Group IV Photonics , 14-16 September, London, United Kingdom, 2011.
Crediti Acquisiti: 13 Mesi presso la Glasgow Univesity, Glasgow, United Kingdom: 60 Corso Solid State Electronics: 90