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

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 14th IEEE International Conference on Telecommunications 8th IEEE Malaysia International Conference on Telecommunications Penang, Malaysia, 14th - 17th May 2007

2. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

3. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

4. Introduction 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

5. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

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

7. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

8. 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 3

9. 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. 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. 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. 3-input AND gate based on SOA-FWM (5) Output power • Output power is given by where GX is the SOA gain in X-polarisation, R() is the conversion efficiency function (nonlinear) 7

13. 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. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

15. Simulations (1) Simulation parameters SOA parameters Parameters Values Laser chip length 600.0  10-6 m Active region width 3.0  10-6 m Active region thickness 40.0  10-9 m Confinement factor 0.56 Group effective index 3.7 Material linewidth enhancement factor 3.0 Differential 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 s Carrier capture time constant 70.0  10-12 s Carrier escape time constant 140.0  10-12 s Gain peak frequency 196.0  1012 Hz Gain coefficient spectral width 1.0  1013 Hz Population inversion parameter 2.0 Initial carrier density 1.0  1024 m-3 Injection DC current 200 mA Parameters Values X1 signal frequency - f1 193.1  1012 Hz X2 signal frequency - f2 193.4  1012 Hz X3 signal frequency - f3 194.1  1012 Hz X1 pulse peak power - P1 2 mW X2 pulse peak power - P2 2 mW X3 pulse peak power - P3 2 mW Pulse-width 5 ps Output filter frequency – f0 194.4  1012 Hz (at f0 = f2 + f3 – f1) Filter bandwidth - B0 140  109 Hz 8

16. Simulations (2) VPI simulation schematic 9

17. 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

18. Simulations (4) Two/three-input AND gate performance (10 Gbit/s) • 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 - - - 2-input AND gate 3-input AND gate Pout rAMron/off 11

19. Simulations (5) Two/three-input AND gate performance (10, 20 and 40 Gbit/s) • Output power:being reduced at high speed due to slow SOA gain recovery • Therefore • Amp. modulation ratio andOn/off contrast ratio are reduced - - - 2-input AND gate 3-input AND gate Pout rAMron/off 12

20. Presentation Outline • Introduction • SOA nonlinearities and FWM • Three-input AND gate based on SOA-FWM • Simulations • Summary

21. Summary • SOA-FWM AND gate features • Multiple-input logic AND gates • Simple implementation • Low power consumption • Integration capability (SOA size ~ m) • SOA-FWM AND gate issues • Low wavelength conversion ratio • Speed is limited by SOA gain recovery 13

22. Acknowledgement Northumbria University for sponsoring this research 14

23. Thank you! Any Questions? 15