1. Optimisation of the Key SOA Parameters for Amplification and Switching
By:
Supervision Team:
Ahmed Abd El Aziz Shalaby
Dr. Wai Pang Ng
Prof. Zabih Ghassemlooy
Prof. Moustafa Hussien

2. Core Network
Proposed core optical router
Source / target node

3. Introduction
All-optical router

4. Introduction
Symetric Mach-Zehnder Interferometer(SMZI)

5. Research Aim

6. Research Aim
To design a bi-directional SMZ and implement it in the router to reduce components, time and cost.

7. Challenges
To optimize the performance of the SOA to be adapted for bi-directional operation.
To overcome the slow time recovery of the SOA gain.
To propose a bi-directional model for the SOA.
To design a bi-directional model for the SMZ and implement it in the proposed router.

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

9. SOA structure

10. Segmentisation model of the SOA
t=l/vg
t=L/vg Ni
input signal
output signal
segment1
segment2
…………..
…………….
segment5
N(1)
N(5)

11. Results
Normalised gain response of the SOA with no input signal.

12. Results
Injection of the input pulse
Normalised gain response of the SOA due to the injection of a short input pulse.

13. Results
Injection of the continuous wave
Normalised gain response of the SOA due to the injection of a continuous input signal.
Saturation gain

14. SOA as an Amplifier

15. SOA for amplification Condition: Note:
The signal should not be affected by the SOA nonlinear effect (i.e: SOA gain depletion should not reach saturation value).
Note:
The reference is the saturation value for a 1mW continuous input signal.

16. SOA for amplification
The output gain corresponding to the input power at different bias currents.
Reference saturation gain:
at I=150mA
at I=200mA
at I=250mA

17. SOA as a Switch

18. SOA for switching Condition: Note:
The signal should be affected by the nonlinearity of the SOA and achieve a 180o phase shift for the deconstructive interference. (i.e: SOA gain depletion of a control pulse (CP) should reach the gain saturation value).
Note:
A control pulse (CP) is required to be launched to the SOA, then the input signal should be injected in order to achieve the 180o phase shift.

19. SOA for switching
The saturation control pulse (CP) for the corresponding input power at different bias currents.

20. SOA Gain Recovery

21. SOA gain recovery
SOA gain dependence on the bias current.

22. SOA gain recovery
Recovery time
Normalised gain response of the SOA due to the injection of a short input pulse.

23. SOA gain recovery
Normalised gain response of the SOA due to partial increase of the bias current.

24. SOA gain recovery t=0 t=l/vg t=L/vg Partial increase of bias current
segment1
segment2
…………..
…………….
segment5
Propagating input signal
Propagating output signal

25. SOA gain recovery
SOA gain recovery due to the additional of different bias currents.
Recovery time=37ps
Improvement of:
86% for 95% recovery
90% for 99% recovery
84% for 100% recovery

26. SOA gain recovery SOA bit rate due to the additional bias current.
SOA bit rate= Gbps
Improvement of:
7.5 times at 95% recovery

27. SOA gain recovery Time needed to apply additional bias current.
35ps for 90mA
154ps for 10mA

28. Current Work

29. Bi-directional SOA model

30. Bi-directional SOA model
t=l/vg
t=L/vg
Propagating output signal
Propagating input signal
segment1
segment2
…………..
…………….
segment5
Co-propagating output signal
Co-propagating input signal

31. Bi-directional SMZ design

32. Uni-directional SMZ

33. Bi-directional SMZ

34. Future Work

35. Future work Practical work on the SMZ.
The replacement of active components in the router by passive components (FBGs) such as demultiplexing, add/drop devices, filtering, and switching .
Solving the contention resolution problem using a novel multiplexing solution.

36. Conclusion The SOA is modelled using a segmentation method.
The effect of input parameters on the gain and carrier density response of an SOA is presented.
Optimum performance conditions are investigated in which the SOA can be used as a standalone amplifier and in a SMZ switch.
The dependence on of the SOA on the bias current is presented.

37. Conclusion
Results show an acceleration in the gain recovery time due to partially increasing the bias current applied to the SOA.
SOA gain recovery time and bit rate corresponding to the additional bias current is investigated.

38. Thank You

39. Thank you