Prototype Photonic Integrated Circuit (ProtoPIC) Platform

and Applications

Dr. David Kharas

MIT Lincoln Laboratory

6 March 2018

Materials Integration: from Nanoscale to Waferscale

This material is based upon work supported by the Assistant Secretary of Defense for Research and Engineering under Air ForceContract No. FA8721-05-C-0002 and/or FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Assistant Secretary of Defense for Research and Engineering.

Distribution Statement A: Approved for public release: distribution unlimited.

© 2018 Massachusetts Institute of Technology.

Delivered to the U.S. Government with Unlimited Rights, as defined in DFARS Part 252.227-7013 or 7014 (Feb 2014). Notwithstanding any copyright notice, U.S. Government rights in this work are defined by DFARS 252.227-7013 or DFARS 252.227-7014 as detailed above. Use of this work other than as specifically authorized by the U.S. Government may violate any copyrights that exist in this work.

ProtoPIC - 2DK 03/06/18

• Motivation

• Integrated Photonics Platforms at Lincoln Laboratory

• Hybrid Integration and ProtoPIC

• Applications

Outline

ProtoPIC - 3DK 03/06/18

Photonic Integration in the Commercial Space

• Photonic integrated circuits (PICs) enable manipulation of light on a chip

– Commercial driver: Internet/Telecom

– Silicon photonics incorporate on-chip modulators and photodetectors, but no native light sources!

– Challenge: Hybrid integration of III-V lasers

• Light enables higher data speeds with less power consumption

Discrete Optical Components Chip-Scale Integration

ProtoPIC - 4DK 03/06/18

Photonic Integration in Other Domains

Electronic-PhotonicIntegration Technology

Inertial Sensors

Microwave Systems Laser Radar

Optical Imaging

Quantum Information

Free-Space Lasercom

High-Energy LasersChem/Bio Sensors

ProtoPIC - 5DK 03/06/18

Photonic Integration in Other Domains

Electronic-PhotonicIntegration Technology

Inertial Sensors

Microwave Systems Laser Radar

Optical Imaging

Quantum Information

Free-Space Lasercom

High-Energy LasersChem/Bio Sensors

ProtoPIC - 6DK 03/06/18

Electronic-Photonic Integration Development Resourcesat Lincoln Laboratory

• InP, GaAs, GaN, Diamond • Optoelectronic Components• Emitter and Detector Arrays• III-V Photonic Integration

• 200 mm Silicon Fab Toolset• 90 nm CMOS and Silicon and Nitride Photonics• Wafer-Scale 3D Integration• Multi-Project Runs

• Precision Flip-Chip Packaging• Laser-Welded Fiber Pigtailing• Reliability and Lifetime Testing• Heterogeneous Hybrid Integration

InP Laser Wafer50 mm Diameter

Silicon PIC Wafer200 mm Diameter

Microelectronics Laboratory

III-V Fabrication Cleanroom

Back-end Processing Cleanroom

Electronic-Photonic Packaging

Materials Growth (III-V, Diamond)

Trusted Foundry

ProtoPIC - 7DK 03/06/18

Photonic Components at Lincoln Laboratory

Compound Semiconductor (III-V) Photonic Integration

Silicon and Silicon Nitride Photonic Integration

III-V to Si Hybrid Integrationand Electronic-Photonic Integration

Gratings

ModulatorsLasers and Optical

Amplifiers

Si Photonics+ CMOS

III-V Laser+ CMOS Driver

Hybrid Si/III-VWafer Bonding

Waveguides and Optical Filters

Photodiodes and Modulators

Photodiodes

Monolithic III-V PICs

Materials: InP, GaAs, GaN, Diamond

Multi-ProjectFab Runs

Optomechanics(MEMS + NEMS)

Materials: Si, SiNx, Al203, Ge

200 mm

SiN Photonics+ III-V Laser

InPLasers

ProtoPIC - 8DK 03/06/18

Reconfigurable Silicon Nitride (SiNx) Photonic Integrated Circuits (PICs)

Image of SiNx/SiO2-on-Silicon PIC Fiber Pigtailed SiNx PIC on Printed Circuit Interface Board

• Operating wavelength ~1550 nm

• Fabricated using MIT LL’s 200 mm silicon fabrication toolset

• SiNx PIC contains ~80 components:

Adiabatic 3-dB couplers

1-to-N power dividers

Ring resonators

Mach-Zehnder modulators

Thermo-optic phase shifters

15 mm

Reconfigurable Optical Filter Response

ProtoPIC - 9DK 03/06/18

Semiconductor Waveguide Optical Gain Media

Slab

Standard Rib Waveguide

•High gain (30 dB)•Mode propagation in QW layer leads to high loss

and limits power to <100 mW• Small mode 1 × 3 m size complicates optical coupling

Semiconductor Optical Amplifiers (SOA) and Lasers• III-V compound semiconductor p-i-n diode structures that use quantum wells (QW)• Can act as an optical amplifier or an emitter source• Optical mode is confined by a sandwich of lower refractive index materials

Slab-Coupled Optical Waveguide Amplifier (SCOWA)

•Moderate gain (15 dB)•Propagation in slab with low loss – higher power >1 W• Large mode 5 × 5 µm improves coupling tolerance

ProtoPIC - 10DK 03/06/18

Field Demonstration of SCOWA Emitter Technology

Methane-Emission Mapping Demonstration (September 2017)

Integrated 3D Lidar and

Gas SensorPackaged

1.65-μm SCOWA

CH4 Leak Rate = 30 scfh

Lincoln Laboratory SCOWA technology has been flight tested

Methane (CH4) Concentration Map

ProtoPIC - 11DK 03/06/18

Prototype Photonic Integrated Circuit (ProtoPIC)

Goal: Create a platform for hybrid integration of III-V components with SiN photonics

Concept: • Create a SiN PIC with a recess to receive a III-V device• Flip chip (FC) bond III-V die with indium bumps• Vertical alignment with mechanical stops• Fiducials to enable sub-micron lateral alignment

Upper CladSiN WGLower CladBottom Dielectric

Indium Solder Bumps

Silicon Nitride PIC on Silicon

Mechanical Stops

III-V WaveguideDevice

Upper CladInGaAsP WG

Lower Clad

Transverse Mode

ProtoPIC - 12DK 03/06/18

Prototype Photonic Integrated Circuit (ProtoPIC)

Goal: Create a platform for hybrid integration of III-V components with SiN photonics

Concept: • Create a SiN PIC with a recess to receive a III-V device• Flip chip (FC) bond III-V die with indium bumps• Vertical alignment with mechanical stops• Fiducials to enable sub-micron lateral alignment

Upper CladSiN WGLower CladBottom Dielectric

Indium Solder Bumps

Silicon Nitride PIC on Silicon

Mechanical Stops

III-V WaveguideDevice

Flip Devicefor Flip Chip Bonding

ProtoPIC - 13DK 03/06/18

Prototype Photonic Integrated Circuit (ProtoPIC)

Goal: Create a platform for hybrid integration of III-V components with SiN photonics

Concept: • Create a SiN PIC with a recess to receive a III-V device• Flip chip (FC) bond III-V die with indium bumps• Vertical alignment with mechanical stops• Fiducials to enable sub-micron lateral alignment

Upper CladSiN WGLower CladBottom Dielectric

Silicon Nitride PIC on Silicon

Indium Solder Bumps

III-V WaveguideDevice

Flip Devicefor Flip Chip Bonding

ProtoPIC - 14DK 03/06/18

PROTO2SL lot after waveguide and grating etch:

4 waveguides at slot junction waveguides with gratings SEM image of 250nm grating posts

ProtoPIC Hybrid Integration Submount

InP SCOWA Insert Devices

Silicon Nitride PIC on Silicon

Bragg Gratings

SEM Image of Input Facet

ProtoPIC Submount

14InsertSlots

8mm

~1 µm Placement

Lateral Offset (Microns)

Bond Campaign

1

0

-1

-2

-3

-4

ProtoPIC - 15DK 03/06/18

100

101

102

103

104

105

102

103

104

105

106

107

108

109

Proto-PIC

External Cavity Laser

RIO Laser

Fre

qu

en

cy

No

ise

(H

z2/H

z)

Offset Frequency (Hz)

-70

-60

-50

-40

-30

-20

-10

0

1350 1450 1550 1650

dB

Wavelength (nm)

ProtoPIC Hybrid LaserOptical Spectrum

ProtoPIC Hybrid Laser with Narrow Line Width

10 mW

90 mW at 2A Bias

40 kHzLine Width

Hybrid Laser Array (Top View)

Line width on par with commercial laser but with 9 higher power

Line Width Measurement

SiNx PIC

ProtoPIC - 16DK 03/06/18

Photonic Integrated Resonant Accelerometer (PIRA)

250 µm

Modulated

Signal

Output

Laser

Input

Optical Microresonator

(Diameter = 20 μm)

• Integration of mm-scale proof mass + micron-scale tether + silicon photonics

• Present performance is on par with compact commercial accelerometers: Measured ~3 µg/√Hz sensitivity

• Path to <100 ng/√Hz – best compact accelerometer

Output

Coupler

Optical Wavelength

Op

tic

al

Tra

ns

mis

sio

n

𝝀𝟎

Strain

Schematic Transmission-Spectra

of Microresonator

Waveguide

2 mm

Proof Mass

Sensing Tethers

Vibrational Motion

ProtoPIC - 17DK 03/06/18

Non-Mechanical Optical Beam-Steeringfor Compact 3D Lidar Imaging

Integrated Beam-Steering System

Initial Demo of 16-Channel Planar-Lens Element

SwitchingInput Port

Nanolidar for Ultra-Small Platforms

SweepingWavelength

Input PortSets Azimuth

WavelengthSets Elevation

Low-Cost Lidar for Self-Driving Cars

ProtoPIC - 18DK 03/06/18

Future Direction: Trapped Ion Quantum Computing

Dual-cell physical architecture concept

Two-species ion chain

2D ion trap array on multilayer chip

Testing of CMOS electronic control

Ion quantum control with photonics integrated on chip trap

Ion trap with integrated APDs and CMOS

Sr+

Ca+

ProtoPIC - 19DK 03/06/18

Future Direction: Laser Light Sources for Wafer Satellite Propulsion

1 m

Power Conditioning

Phased Array with Uniform Top-Hat

Profile

Optics Array for High Fill Factor

Phase Control

Thermal Management

ProtoPIC Seed Distribution to a Semiconductor Optical Amplifier Array

Light Sail

Wafer Satellite

Star Shot Missionto Alpha Centauri

Propulsion Laser Array

3 cm

ProtoPIC - 20DK 03/06/18

• MIT Lincoln Laboratory has developed a library of photonic component technologies

– SiN and silicon photonics, waveguides, splitters, modulators, thermal tuners, and filter architectures

– III-V SCOWA amplifiers, lasers, photodiodes, modulators

• Recently developed a flexible hybrid integration platform ProtoPIC that can be used to combine a variety of III-V devices with our SiN PICs

– Flip chip III-V attach with ~1 µm placement capability

– Initial applications of the technology have been applied to demonstrate an extended cavity hybrid laser with narrow line width 40 kHz and 90 mW optical power

• The technology is amenable to adoption for a wide variety of applications

Summary