All-Optical Logic

K.J.Blow

Aston University, UK

Outline

• Some history

• all-optical devices

• bit-serial processing

• regenerative memory

• packet receiver design

Optical Logic, the history

• Nonlinearity– Giant n

2

• Slow so go for parallel– SEED devices

• Problems with spatial crosstalk

– Ultrafast• Small nonlinearity

“The fourth quadrant”

ELECTRONICS PHOTONICS

ANALOGUE

DIGITAL

FDM:manipulation of modulated carriers(1950s)

Electronic digital processing:direct manipulation of bits

WDM:manipulation of modulated carriers

Optical digital processing:direct manipulation of bits

Why all-optical?

• Not speed– electronics is pushing 100GHz

• Scalable architecture– time of flight systems– bit serial computer (Colorado)

• New techniques– all-optical regenerator– use of RZ pulses

Optical Loop MirrorsNonlinearity

WDM

Coupler

Input

WDM

Transmission

Reflection

Control

NOLM achievements

• Soliton switching

• all-optical demultiplexing

• add-drop multiplexers

• all-optical sampling oscilloscope

• all-optical regeneration

• re-configurable node

Key Properties

• Speed– all-fibre, ~100fs

– SOA, ~10ps

• Switching power/energy– all-fibre, 1W km

– SOA, 100fJ

• ResponseR=

12{1+ cos (Δ ϕ)}

Time of flight

• Design system taking c into account

• No static memory

• Bit rate can increase by integer multiples

• Virtual machines can be multiplexed

• Colorado computer– http://albert.colorado.edu/~straub/spoc/spoc.html

Feedback/forward

• Feedback– 100GHz, bit separation of 3mm

– allows re-use of gates

• Feedforward– needs more gates

– only differential time shifts

All-Optical Regenerator

data

modulated clock(regenerated data)

isolator

Erbiumamplifier

filter

clockout

data in

Clock laser Loop Mirror

old data out

Regenerative Memory

DFB

TOAD

Data

TOAD

DFB

Delay

Experimental details

• Two SOA based all-optical nonlinear gates (TOAD/SLALOM)– switching energy < 1pJ per pulse

• Wavelength switching - 1533nm/1551nm• Memory loop ~ 1000 bits• Stable for several hours

– ( >10 billion circulations)

• Thresholding operation possible

Threshold properties

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Normalised phase shift (π radians)

Tra

nsm

issi

on

1235

Storage threshold - change by altering induced phase shift

Amplituderestoration

Upper - input data patternLower - stored data pattern

01001000Fixed

Variable

• Amplitude restoration of pulses above the memory storage threshold& well defined threshold level

2 ns

10100101

• Increasing induced phase shift produced by pulses lowersmemory threshold for same input pattern

Upper - input data patternLower - stored data pattern

2 ns

Pseudo-random number generation

• Standard shift register approach

Optical Implementation

I/P O/P

I/P O/P

Switch I/P

Switch I/P

TOAD2

TOAD1

DFB#1 1552nm clock pulses

~10ps @ 1GHz

DFB#2 1534nm clock pulses

~12ps @ 1GHz

90:10 50:50 50:50

attenuator

EDFA#1 #3

#2monitor O/P

EA modulator

PRBS ‘initiate’ pulse

fibre delay

Optical delay line

Results

Experimental and Theoretical pulse sequences

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (ns)

Multiplexed PRNGs

0 200 400 600 800 1000 1200 1400 1600 1800 2000

-16.0

-18.0

-20.0

-22.0

-24.0

-26.0

-28.0

-30.0

Frequency (MHz)

Pow

er (d

Bm

)

-12.0

-14.0

-16.0

-18.0

-20.0

-22.0

-24.0

-26.0

-28.00 200 400 600 800 1000 1200 1400 1600 1800 2000

Frequency (MHz)

Pow

er (

dBm

){713,552} ≡ 23 × {31,24}

Corresponding to 23 temporally multiplexed 231-1 sequence generators

These can be synchronous or asynchronous

All-Optical Counting

. ... ..001 ..001

COUNT (m bit)

CARRY (m-1 bit)

m bit

INPUT

OUTPUT

.

clock

clock

m bit

XOR

AND

Experimental Implementation

TOAD1

Switch I/P

I/P O/P

TOAD2

Switch I/P

I/P O/P

TOAD3

Switch I/P

I/P O/P

TOAD4

Switch I/P

I/P O/P

EDFA

Opticaldelayline

50:50

50:50

90:10

COUNT Output

DFB#1

DFB#2

DFB#2

COUNT memory (297 bits)

CARRYmemory

(296 bits)

EAM

Input bitsto be counted

Fibredelay

XOR

AND

Electricaldata

Results

• Movies of experiments– Short sequence 5 bits shown

– Full sequence

Bit serial components

• Delay line

• Combiner

• TOAD 0,2π

π

Regenerative Memory

• e.g. to store an address

Ones

Address

ADDRESS

Window Generator

Window

1 bit delay

Ones

Sync

Word Comparison

CorrectWord

1 bit delay

Initialise

A B

Ones with reset

Packet Receiver (a)

Ones

Address

Sync

ADDRESS HEADERWINDOW

ONESWITHRESET

RESET

OnesOnes

Packet Receiver (b)

Packet

HEADERWINDOW

PAYLOAD

HEADER

ADDRESS

ONES WITH RESET

Sync

CORRECT HEADER

PacketPASS

EXTRACT

Simulation

ADDRESS

HEADERWINDOW

DATA

HEADER

CORRECTHEADER

EXTRACT

PASS

The future

• Integration is the key– integrated MZ interferometer

• HHI• ETH Zurich

• Single bit feedback– allows line rate bit serial processing

• Feed forward techniques– use more gates

BT Bit Serial Work

• All-optical circulating shift register using a semiconductor optical amplifier in a fibre loop mirror

– A. J. Poustie, R. J. Manning, and K. J. Blow, Electron. Lett., 32 1215 (1996)

• All-optical clock division using a semiconductor optical amplifier loop mirror with feedback

– R. J. Manning, A. J. Poustie, and K. J. Blow, Electron. Lett., 32 1504 (1996)

• Nonlinear loop mirrors with feedback and a slow nonlinearity– K. J. Blow, R.J. Manning and A. Poustie, Opt. Commun., 134 43 (1997)

• All-optical regenerative memory for long term data storage– A. J. Poustie, K. J. Blow and R. J. Manning, Opt. Commun., 140 184 (1997)

• Semiconductor Laser Amplifiers for Ultrafast All-Optical Signal Processing

– R. J. Manning, A. D. Ellis, A. Poustie and K. J. Blow, JOSA B, 14 3204 (1997)

• Storage threshold and amplitude restoration in an all-optical regenerative memory

– A. Poustie, K. J. Blow and R. J. Manning, Opt. Commum., 146 262 (1998)

• Model of longitudinal effects in semiconductor optical amplifiers in a nonlinear loop mirror configuration

– K. J. Blow, R. J. Manning and A. J. Poustie, Opt. Commun., 148 31 (1998)

• Wavelength dependence of switching contrast ratio of a semiconductor optical amplifier based nonlinear loop mirror

– R. J. Manning, A. E. Kelley, A. Poustie and K. J. Blow, to be published Electron. Lett.

• All-optical regenerative memory with full write/read capability– A. J. Poustie, A. E. Kelley, R. J. Manning, and K. J. Blow, submitted to Opt. Commun.

Optical Logic, the history

• Nonlinearity– Giant n

2

• Slow so go for parallel– SEED devices

• Problems with spatial crosstalk– Ultrafast

• Small nonlinearity

Pseudo-random number generation

• Standard shift register approach

Optical Implementation

I/P O/P

I/P O/P

Switch I/P

Switch I/P

TOAD2

TOAD1

DFB#1 1552nm clock pulses

~10ps @ 1GHz

DFB#2 1534nm clock pulses

~12ps @ 1GHz

90:10 50:50 50:50

attenuator

EDFA#1 #3

#2monitor O/P

EA modulator

PRBS ‘initiate’ pulse

fibre delay

Optical delay line

Results

Experimental and Theoretical pulse sequences

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (ns)

Multiplexed PRNGs

0 200 400 600 800 1000 1200 1400 1600 1800 2000

-16.0

-18.0

-20.0

-22.0

-24.0

-26.0

-28.0

-30.0

Frequency (MHz)

Pow

er (d

Bm

)

-12.0

-14.0

-16.0

-18.0

-20.0

-22.0

-24.0

-26.0

-28.00 200 400 600 800 1000 1200 1400 1600 1800 2000

Frequency (MHz)

Pow

er (

dBm

)

{713,552} ≡ 23 × {31,24}

Corresponding to 23 temporally multiplexed 231-1 sequence generators

These can be synchronous or asynchronous

All-Optical Counting

. ... ..001 ..001

COUNT (m bit)

CARRY (m-1 bit)

m bit

INPUT

OUTPUT

.

clock

clock

m bit

XOR

AND

Experimental Implementation

TOAD1

Switch I/P

I/P O/P

TOAD2

Switch I/P

I/P O/P

TOAD3

Switch I/P

I/P O/P

TOAD4

Switch I/P

I/P O/P

EDFA

Opticaldelayline

50:50

50:50

90:10

COUNT Output

DFB#1

DFB#2

DFB#2

COUNT memory (297 bits)

CARRYmemory

(296 bits)

EAM

Input bitsto be counted

Fibredelay

XOR

AND

Electricaldata

Results

• Movies of experiments– Short sequence 5 bits shown– Full sequence