By: Other AuTHORS :

1. The Impact of The Input Energy on The SOA Gain with Non-uniform Biasing By: Other AuTHORS: Ahmed Abd El Aziz Shalaby Dr. Wai Pang Ng Prof. Zabih Ghassemlooy Prof. Moustafa Hussien (Arab Academy for Science and Technology, Egypt) Dr. RazaliNgah (UniversitiTeknologi, Malaysia)

2. Presentation Outline • Introduction • All-optical packet switching • All-optical router • Mach-Zehnder Interformeter(MZI) • SOA structure • Problem • Proposed • Our proposal

3. Presentation Outline • Segmentisation model • Uniform biasing • Non-uniform biasing • Triangular bias current • Sawtooth bias current • Comparison between uniform and non-uniform biasing techniques • Conclusions

4. Introduction

5. All-optical packet switching

6. All-optical router

7. Mach-Zehnder Interformeter (MZI)

8. Mach-Zehnder Interformeter (MZI) Symmetric Mach-Zehnder (SMZ)

9. Mach-Zehnder Interformeter (MZI) • Advantages of SMZ • Narrow and square switching window • Compact size • Thermal stability and low power operation • High integration potential • Strong nonlinearity characteristics

10. Output signals Injection current (I) Output facet L Input facet of active region Input signals SOA structure w H

11. SOA structure

12. Problem • For high-speed applications, the SOA must have a fast gain recovery time to avoid system penalties arising from bit pattern dependencies. The gain recovery of the conventional SOAs is limited by the long carrier-recovery time.

13. Proposed • The slow gain recovery can be improved by increasing the injected bias current, the device length or by changing the pulse width (input energy) of the input signal [5]. Several research groups have reported theoretical and experimental results on externally injected SOAs (assist light or holding beam ) [6,7].

14. Our proposal • Novel non-uniform bias current techniques are injected to the SOA in order to achieve a linear output gain compared to the uniform biasing for ultra-high speed routers.

15. Segmentisation Model

16. Segmentisation model of the SOA t=0 t=l/vg t=L/vg Ni input signal output signal N(1) N(5)

17. Uniform Biasing

18. Uniform Biasing • Normalized SOA gain response to single (doted) and multiple (solid) input pulses.

19. Uniform Biasing • Normalized output gain achieved by successive input pulses.

20. Non-uniform Biasing

21. Non-uniform Biasing • Sawtooth (doted) and triangular (solid) bias currents.

22. Triangular bias current • Normalized SOA gain response to multiple of input pulses using triangular bias current.

23. Triangular bias current • Normalized output gain achieved by successive input pulses using triangular bias current as a ratio of uniform bias current.

24. Sawtooth bias current • Normalized SOA gain response to multiple of input pulses using sawtooth bias current.

25. Sawtooth bias current • Normalized output gain achieved by successive input pulses using sawtooth bias current as a ratio of uniform bias current.

26. Comparing uniform and non-uniform biasing • Gain standard deviation against the input signal energy for uniform (dot-dashed), sawtooth (doted) and triangular (solid) biasing for a range of data rates.

27. Comparing uniform and non-uniform biasing • Improvement of the gain standard deviation upon uniform biasing • For sawtooth bias current: • at 10 Gbps 3.25 dB • at 20 Gbps 0.51 dB • at 40 Gbps min improvement • For triangular bias current: • at 10 Gbps 2.4 dB • at 20 Gbps 0.4 dB • at 40 Gbps min improvement

28. Gain standard deviation against the average sawtooth bias current for 1 fJ input signal energy.

29. Conclusions • We have proposed novel techniques to bias the SOA. • The total gain response of a segmentized SOA model is simulated. • We have investigated applying triangular and sawtooth biasing shapes in order to optimize the gain standard deviation for data rates of 10, 20 and 40 Gbps. • Results showed an enhancement to the gain uniformity achieved using non-uniform biasing, especially sawtooth biasing. • The impact of the input pulse energy on the gain standard deviation and the output gain for all biasing techniques are investigated. • The impact of the average bias current used on the gain uniformity is presented.

30. Thank you