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)

7

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

8

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

9

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)

12

PIN

PT

PC

Variable Bandwidth Filter -φr

Kc Kc

Lr Lr Kr Kr PT

PC ΔL= Lr

φr

13

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

14

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

23

FSRB dB

9/8rK 2/1cK

Power Coupling Coefficients

Symmetric Interleaver [Literature]

NO Bandwidth Tunability

/2

15

Inte

nsi

ty [

dB

]

Wavelength [nm]

Working Principles

23

FSRB dB =π/2

3/2rK 2/1cK

Power Coupling Coefficients

Symmetric Interleaver [Our Work]

NOW Bandwidth Tunability

16

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

17

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

19

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

20

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

22

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%

23

-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

24

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

25

PROJECT SAPPHIRE Shared Access Platform to PHotonic Integrated REsources

Unità Coinvolte:

Fonderia:

26

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