Ray T. Chen, used with permission only

Advances in Optical InterconnectsRay T. Chen

Microelectronics Research CenterThe University of Texas, Aust

SanYa, China12/22/2009

Ray T. Chen, used with permission only2

Introduction:Projection of Bandwidth

Ray T. Chen, used with permission only

Polymer-based Photonic Technology & Business Structure

Ray T. Chen, used with permission only

Fully Embedded Board Level Fully Embedded Board Level Optical InterconnectionOptical Interconnection

45 micro-mirror

Cu Trace

Unique Architecture for Optical PWB (Printed Writing Board) ; All the optical components are interposed inside the PCB Solve the package problem / Reduce Cost Effects

VCSEL array

Micro-via

Optical PCB

1x12 PIN Photodiode

12-channel Polymer Waveguide [109 cm ]

1x12 VCSEL

Ray T. Chen, used with permission only

2 mm

Lamination of Optical Waveguide FilmLamination of Optical Waveguide Film & Integration of Thin Film VCSEL & Integration of Thin Film VCSEL

12-Channel Polymer Waveguide & 45o Micro-Mirror

Optical Layer (~170 m)

PSA (Pressure Sensitive Adhesive) Film (100 / 200 m)

PCB Substrate

250m

Cross Section View of Laminated Optical Layer

Cu Transmission Lines for VCSEL (or PD) Integration

PCB Sub

PCB Sub

Cu Trans. Lines(thickness = ~ 10 m)

PSA filmOptical layer

VCSEL

Optical Layer

Optical LayerVCSEL

Bottom Emitting VCSEL

Top Emitting VCSEL

- PSA (Pressure Sensitive Adhesive) Film : 100 / 200 m- Optical Waveguide Film Layer = ~ 170 m

via

Ray T. Chen, used with permission only

Polyimide Based 1-to-48 Fanout H-tree Optical Waveguide on Si-Substrate

(c)

Ray T. Chen, used with permission only

System Integration with VCSELs and Photodiodes

L = 3200 um W = 485 umH = 200 um Pitch = 250 umAperture = 15 um, 10Gbps

L = 3335 um W = 690 umH = 200 um Pitch = 250 umAperture = 70 um, 2.5Gbps

Thin film waveguide on flexible substrate

VCSEL Photodiode

Ray T. Chen, used with permission only

Opal, the best known periodical structure in nature.

Photonic Crystal structure in nature

Ray T. Chen, used with permission only

PCW

* Dark region: electrode/pad

80 μm

PCW line defect

NP

Electrodes

Gigahertz p-i-n Diode Embedded Silicon Photonic Crystal Mach Zehnder Interferometer (MZI) Modulator

9

electrodes

PCW

ModulationDepth 92%

Simulation

slow vg

Optical Performance

Modulation trace(1GHz, square wave)

I-V curve of photonic crystal p-i-n diode

Electrical Characterization

Key features• Slow light in Photonic Crystal Waveguide (PCW) to enhance modulation by up to 40X•Unique electrode routing for on-chip integration with driver•Faster speed due to the enhancement of injection current density by downscaling

the device size

Current injection

Electrode

P+

Anode

+ -Cathode

N+Intrinsic region

--Lanlan Gu, W. Jiang, X. Chen, L. Wang, and R. T. Chen “High speed silicon photonic crystal waveguide modulator for low voltage application,” Applied Physics Letters, 90, 071105 (2007).

Ray T. Chen, used with permission only

2-D Image 3-D Image

Rough sidewall without post-etching oxidation

Focus Ion Beam (FIB) nano-polished endface

High smoothness, exact round shape

JEOL JBX-6000FS/E E-Beam Nano-Lithography

FEI Strata DB235 Dual Beam SEM/FIBNano-characterization System

Plama-Therm 790 Si and SiO2 Reactive Ion Etching (RIE)

SEM Micrographs & Key Facilities

Ray T. Chen, used with permission only11

Progress of Silicon Nanophotonics

Integrated APD+TIACampbell

Raman λ Conv.

UCLA

1 Gb/sec Si Modulator

Intel

10Gb/sec Si Modulator Intel/Luxtera

1Gb/s PCW Modulator (20 pJ/bit)

UT

10Gb/s PIN Modulator (5 pJ/bit)

IBM

Dual Grating Directional Coupling

Surrey

30 GHz Si-Ge Photo-

detector IBM

39 GHz Si-Ge Photo-delector U. Stuttgart

Broadband Amplifier

Cornell

30Gb/sec Si Modulator

Intel

>1Gb/s CAP Modulator

(0.54 pJ/bit) UT

Inverted Taper

NTT, Cornell

Low power PCW

Modulator IBM & UT

Hybrid Si Laser

UCSB/intel

Si Nano-membrane Array

UIUC

Cascaded Si Raman Laser

Intel

PCW Loss < 25 dB/cm

IBM

PCW Loss < 7 dB/cm IBM, Festa,

NTT

PCW Loss < 3dB/cm

NTT

20dB loss reduction for

slot-PCW UT

2002 2003 2004 2005 2006 2007 2008

The highlight research projects are accomplished by Nanophotonics and Optical Interconnects Research Lab at UT-

Austin

Ray T. Chen, used with permission only

MURI-Center for Silicon Nano-Membranes

Name of Principal Investigator

School

Ray Chen (Lead) UT Austin

Seth Bank UT Austin

Wei Jiang Rutgers

Fabiab Pease Stanford

John Rogers UIUC

Gennady Shvets UT Austin

Emanuel Tutuc UT Austin

Scientific novelty and Uniqueness:Nanomembrane lithography to form 3D well-aligned silicon nanomembranesManufacturable process to form nanowires, photonic crystal waveguides and plasmonic structures on nanomembranes2D Ultracompact phase locked laser array on silicon as a light source for Optical Phased Array (OPA)Ultracompact structure provides large steering angles to ± 70o in both azimuth and elevation directions for Optical Phased Array (OPA)Slow photon in PCW provides a group index above 300 and provides tunable delay time from 0 to 32 nsecs suitable for phased array antenna applications

Ray T. Chen, used with permission only

Detailed Approaches

sourcewafer

print

3D-HGI

device substrate

stamp

0 1 2 30.0

0.4

0.8

3V

2V

0V-6 -3 0 3 6

0

50

100

10-2

100

102

I DS(m

A)

VGS(V)

I DS(

A)

VDS(V)

1st

2nd

3rd

G DS

200 m

Transfer printing of nanomembranes that contain nanostructured waveguides Demonstrated 3-layer devices

Use electrostatic forces to align 3D membrane stack to a small fraction of a micron. Many variations are possible:• An interfacial fluid layer to allow lateral motion• A Langmuir-Blodgett trough is already installed for the deposition of mono-& oligo-layers.

thin (<100nm) sliver of crystalline diamond made by FIB. Then the FIB then ‘tacked ‘ it into place again using deposition of Pt to provide the tacks