1. 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, NCRLab Northumbria University, Newcastle, UK 14 th IEEE International Conference on Telecommunications 8 th IEEE Malaysia International Conference on Telecommunications Penang, Malaysia, 14 th - 17 th May 2007

2. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

3. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

4. ICT-MICC 2007 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

5. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

6. ICT-MICC 2007 SOA Nonlinearities 1. Cross gain modulation 2. Cross phase modulation 3. Four-wave mixing 2

7. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

8. ICT-MICC 2007 3-inputs AND gate based on SOA-FWM (1) Operation Principle M different inputs X m at different M frequencies  m Output Y is “1” only when all the inputs are non-zeros 3

9. ICT-MICC 2007 3-inputs AND gate based on SOA-FWM (2) Multi-tone Output N frequency components are generated: Output Y is selected at  o such that the component consists of all  m contributions 4

10. ICT-MICC 2007 3-inputs AND gate based on SOA-FWM (3) 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. 5

11. ICT-MICC 2007 3-input AND gate based on SOA-FWM (4) Filtering out  o Y could be selected from one of these components  1 +  2 –  3  3 +  1 –  2  2 +  3 –  1 However, for high conversion efficiency,  2 +  3 –  1 is selected (positive detuning) 6

12. ICT-MICC 2007 3-input AND gate based on SOA-FWM (5) Output power Output power is given by where G X is the SOA gain in X-polarisation, R(  ) is the conversion efficiency function (nonlinear) 7

13. ICT-MICC 2007 3-input AND gate based on SOA-FWM (6) 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” 7

14. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

15. ICT-MICC 2007 Simulations (1) Parameters Values X 1 signal frequency - f 1 193.1  10 12 Hz X 2 signal frequency - f 2 193.4  10 12 Hz X 3 signal frequency - f 3 194.1  10 12 Hz X 1 pulse peak power - P 1 2 mW X 2 pulse peak power - P 2 2 mW X 3 pulse peak power - P 3 2 mW Pulse-width 5 ps Output filter frequency – f 0 194.4  10 12 Hz (at f 0 = f 2 + f 3 – f 1 ) Filter bandwidth - B 0 140  10 9 Hz Parameters Values Laser chip length600.0  10 -6 m Active region width3.0  10 -6 m Active region thickness40.0  10 -9 m Confinement factor0.56 Group effective index 3.7 Material linewidth enhancement factor3.0 Differential refractive index-1.11  10 -26 m 3 Linear material gain coefficient 3.0  10 -20 m 2 Transparency carrier density 1.5  10 -24 m -3 Nonlinear gain coefficient1.0  10 -23 m 3 Nonlinear gain time constant200.0  10 -15 s Carrier capture time constant70.0  10 -12 s Carrier escape time constant140.0  10 -12 s Gain peak frequency196.0  10 12 Hz Gain coefficient spectral width 1.0  10 13 Hz Population inversion parameter2.0 Initial carrier density1.0  10 24 m -3 Injection DC current200 mA Simulation parametersSOA parameters 8

16. ICT-MICC 2007 Simulations (2) VPI simulation schematic 9

17. ICT-MICC 2007 Simulations (3) AND operation X 1 ( 1 0 1 0 1 1 1 1 0 1 ) X 2 ( 0 1 1 0 1 1 1 0 1 1 ) X 3 ( 0 1 1 0 0 1 1 0 1 1 ) Y ( 0 0 1 0 0 1 1 0 0 1 ) 10

18. ICT-MICC 2007 Simulations (4) Two/three-input AND gate performance (10 Gbit/s) - - - 2-input AND gate  3-input AND gate  Pout  r AM  r on/off Output power: linearly dependent on the input power Amp. modulation ratio (r AM ): the amplitude variation is small ~ 2 dB On/off contrast ratio (r on/off ): in a range of 14 - 22 dB 11

19. ICT-MICC 2007 Simulations (5) Two/three-input AND gate performance (10, 20 and 40 Gbit/s) - - - 2-input AND gate  3-input AND gate  Pout  r AM  r on/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

20. ICT-MICC 2007 Presentation Outline 1.Introduction 2.SOA nonlinearities and FWM 3.Three-input AND gate based on SOA-FWM 4.Simulations 5.Summary

21. ICT-MICC 2007 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

22. ICT-MICC 2007 Acknowledgement Northumbria University for sponsoring this research 14

23. ICT-MICC 2007 Thank you! Any Questions? 15