Photonic Integrated Circuitry - utdallas.edudlm/Duncan Phot ICs Jan 2004.pdf · Photonic Integrated Circuitry Duncan MacFarlane ... – Highly appropriate for MIMO applications 100

The Erik Jonsson School of Engineering and Computer Science

Photonic Integrated Circuitry

Duncan MacFarlaneThe University of Texas at Dallas

Gary EvansSouthern Methodist University

Jack Kilby’s revolutionary integrated circuit


Introduction

g Early electronic filters used only L, C and R’s –“Passive Filters”

g Gain elements, first vacuum tubes, later transistors, allowed “Active Filters”

g Current optical filters are purely passiveg It is time to develop optical filters with gain that are

higher performance, and adaptive

We are developing a manufacturable, programmable, Photonic Integrated Circuit!


Active Lattice Filters

An active optical filter has a gain element that allows the weights associated with the different poles and zeroes to be tuned.

g Lattice Filters good for:– Linear Prediction– Frequency Discrimination– Robust wrt realization

limitations

g Gain allows:– Improved quality factors– Adaptive filters

+

+

+

+

Z-1/2

Z-1/2

G

G

Tk(z)

Rk(z) Rk+1(z)

Tk+1(z)tk

tktk-1

tk-1

-rkrkrk-1 -rk-1

Gain Block Delay Block


Surface Grating Photonic IC

We are using the GSE technology for integrated active optical filters

AlGaInAs/InP Material System w. MQW waveguide/active gain region

electrode electrodeelectrode electrodeInput

Reflected Output

Transmitted Output

SurfaceGrating

Gain AndDelay Stage

Grating

Gain Region


Four Directional Couplers

g Grating can couple in multiple directions– Input/output– Mesh structure

g FIB nanostructureg Holographic lithography

– Two step process– Crossed Gratings


2D GSE Lattices: “Thick Linear”

0 0.2 0.4 0.6 0.8 1-1000

-800

-600

-400

-200

0

Normalized Frequency (×π rad/sample)

Phas

e (d

egre

es)

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1


Mag

nitu

de

0 0.2 0.4 0.6 0.8 1-100

-50

0

50

100


Phas

e (d

egre

es)

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

Normalized Frequency (×π rad/sample)M

agni

tude


Two Dimensional GSE Lattices

Completely new filter structure solved by layer peeling with 2nx2n matrices … Research is benefiting fundamental DSP engineering

~60 um


Two Dimensional GSE Lattices

g Multiple Input, Multiple Output Applications– Add/drop applications, dwdm, o-cdma on same chip– Cross correlators, decouplers, cross-talk cancelation– multi-trajectory tracking, joint process estimation

g Fully Tunable … programmableg Extends the palette of filter realizations for

optimal implementations


Frequency Selection

0 0.2 0.4 0.6 0.8 1-200

-100

0

100

200


Phas

e (d

egre

es)

0 0.2 0.4 0.6 0.8 10

50

100

150

200


Mag

nitu

de

Stable operation withQ >75,000


Bandpass Frequency Tuning via Gain

0.40.5

0.60.7

0.80.9

0.4

0.6

0.8

10.26

0.27

0.28

0.29

0.3

Gx00

Peak Postion vs.Gx00&Gy00

Gy00

Peak

Pos

ition


Economically Viable Device

g Structure is highly manufacturable– Standard Epitaxy– Photolithographic gratings

• Last step in process• No regrowth• Chip scale process (parallel)

– Being commercialized for lasersg Basic structure can be standardized for fabrication

purposes– Individual users may then program them for a particular

application– Just like an FPGA or a DSP


Outcome of the Research Program

g Standardized Photonics– Two dimensional lattice has wealth of transfer functions

supporting widespread applications– Programming determines application

g Basic advances in DSP– Two dimensional structure is new– Highly appropriate for MIMO applications

100 GHz clock rates and GHz tuning rates will enable high volume information engineering applications

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Photonic Integrated Circuitry - utdallas.edudlm/Duncan Phot ICs Jan 2004.pdf · Photonic Integrated Circuitry Duncan MacFarlane ... – Highly appropriate for MIMO applications 100