h. le minh, z. ghassemlooy, wai pang ng and m. f. chiang

Simulations of All-Optical Multiple-Input AND-Gate Based on Four Wave Mixing in a

Single Semiconductor Optical Amplifier

H. Le Minh, Z. Ghassemlooy, Wai Pang Ng and M. F. Chiang

Optical Communications Research Group, NCRLabNorthumbria University, Newcastle, UK

14th IEEE International Conference on Telecommunications

8th IEEE Malaysia International Conference on Telecommunications

Penang, Malaysia, 14th - 17th May 2007

ICT-MICC 2007ICT-MICC 2007

Presentation Outline

1. Introduction

2. SOA nonlinearities and FWM

3. Three-input AND gate based on SOA-FWM

4. Simulations

5. Summary


Photonic Network Transparency High-speed all-optical core router

Processing, switching and routing in optical domain high throughput

Solution: All-optical Boolean logic gates (AND, OR, XOR…)

1

Introduction

Edge Router (Ingress/Egress) with 4-bit address XXXX

Core Router

1011

1010 0110

0111

Client Network

Client Network

1001

XXXX

Low-speed packet

Low-speed packet

High-speed packet

Core Network



1. Introduction



4. Simulations

5. Summary


SOA Nonlinearities

1. Cross gain modulation

2. Cross phase modulation

3. Four-wave mixing

SOA BPF (2)

1

2

Data

CW

Inverted data at 2

1 2

Data

CW

2

SOA1

SOA2

BPF (2)

1

2

1 – 2

SOA

1

2

1 2

21 – 2 22 – 1

2



1. Introduction



4. Simulations

5. Summary


3-inputs AND gate based on SOA-FWM (1)

Operation Principle M different inputs Xm at different M frequencies m

Output Y is “1” only when all the inputs are non-zeros

Ein Eout

WDM multiplexer

X1

X2

XM

SOA

1

2

M

o Y

X1 X2 … XM Y 0 x … x 0 x 0 … x 0 … … … … 0 x x … 0 0 1 1 … 1 1

x: 0 or 1 M-input AND gate

3



Multi-tone Output N frequency components are generated:

Output Y is selected at o such that the component consists of all m contributions

2

)1(2

MMN

4

Ein Eout

WDM multiplexer

X1

X2

XM

SOA

1

2

M

o Y

X1 X2 … XM Y 0 x … x 0 x 0 … x 0 … … … … 0 x x … 0 0 1 1 … 1 1

x: 0 or 1 M-input AND gate



Frequency component generation from 3 input wavelengths Signal beatings 3 – 2, 3 – 1 and 2 – 1 will modulate signals

at 1, 2 and 3, thus resulting in 9 new frequency components

However, only three components contain information of all 1, 2 and 3. Those are: 1 + 2 – 3, 3 + 1 – 2 and 2 + 3 – 1.

1+2– 3

1+1–3 1+1– 2 2+2–3

3+1–2

2+2– 1

2+3–1

3+3–2 3+3–1

1 2

3 2S

2r

1+2– 3

1+1–3 1+1– 2 2+2–3

3+1–2

2+2– 1

2+3–1

3+3–2 3+3–1

1 2

3 2S

2r

5


Eout

o Y X1 X2 … XM Y

0 x … x 0 x 0 … x 0 … … … … 0 x x … 0 0 1 1 … 1 1

x: 0 or 1

3-input AND gate based on SOA-FWM (4)

Filtering out o

Y could be selected from one of these components1 + 2 – 3

3 + 1 – 2 2 + 3 – 1

However, for high conversion efficiency, 2 + 3 – 1 is selected (positive detuning)

6



Output power

Output power is given by

where GX is the SOA gain in X-polarisation, R() is

the conversion efficiency function (nonlinear)

1323X321out 2 RGPPPP

7



Output Amplitude Modulation Ratio: the ratio of the

maximum value over the minimum value of the output

bits “1”

Output On/Off Contrast Ratio: the ratio of the

minimum value of output bits “1” and the maximum of

output bit “0”

min,1

max,1AM P

Pr

max,0

min,1on/off P

Pr

7



1. Introduction



4. Simulations

5. Summary


Simulations (1)

Parameters Values

X1 signal frequency - f1 193.1 1012 HzX2 signal frequency - f2 193.4 1012 HzX3 signal frequency - f3 194.1 1012 HzX1 pulse peak power - P1 2 mWX2 pulse peak power - P2 2 mWX3 pulse peak power - P3 2 mWPulse-width 5 psOutput filter frequency – f0 194.4 1012 Hz (at f0 = f2 + f3 – f1)Filter bandwidth - B0 140 109 Hz

Parameters Values

Laser chip length 600.0 10-6 mActive region width 3.0 10-6 mActive region thickness 40.0 10-9 mConfinement factor 0.56Group effective index 3.7Material linewidth enhancement factor 3.0Differential refractive index -1.11 10-26 m3

Linear material gain coefficient 3.0 10-20 m2

Transparency carrier density 1.5 10-24 m-3

Nonlinear gain coefficient 1.0 10-23 m3

Nonlinear gain time constant 200.0 10-15 sCarrier capture time constant 70.0 10-12 sCarrier escape time constant 140.0 10-12 sGain peak frequency 196.0 1012 HzGain coefficient spectral width 1.0 1013 HzPopulation inversion parameter 2.0Initial carrier density 1.0 1024 m-3

Injection DC current 200 mA

Simulation parameters SOA parameters

8


Simulations (2)

VPI simulation schematic

9


Simulations (3)

AND operation

X1

(1 0 1 0 1 1 1 1 0 1 )

X2

(0 1 1 0 1 1 1 0 1 1 )

X3

(0 1 1 0 0 1 1 0 1 1 )

Y

(0 0 1 0 0 1 1 0 0 1 )

10


Simulations (4)

Two/three-input AND gate performance (10 Gbit/s)

- - - 2-input AND gate 3-input AND gate Pout rAM ron/off

• Output power: linearly dependent on the input power

• Amp. modulation ratio (rAM): the amplitude variation is small ~ 2 dB

• On/off contrast ratio (ron/off): in a range of 14 - 22 dB

11


Simulations (5)

Two/three-input AND gate performance (10, 20 and 40 Gbit/s)

- - - 2-input AND gate 3-input AND gate Pout rAM ron/off

• Output power: being reduced at high speed due to slow SOA gain recovery

Therefore

• Amp. modulation ratio and On/off contrast ratio are reduced

12



1. Introduction



4. Simulations

5. Summary


Summary

SOA-FWM AND gate features– Multiple-input logic AND gates– Simple implementation– Low power consumption– Integration capability (SOA size ~ m)

13

SOA-FWM AND gate issues– Low wavelength conversion ratio– Speed is limited by SOA gain recovery


Acknowledgement

Northumbria University for sponsoring this research

14


Thank you!

Any Questions?

15

h. le minh, z. ghassemlooy, wai pang ng and m. f. chiang

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