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Designing a bi-directional SMZ for efficient optical routing, optimizing SOA performance, and overcoming time recovery challenges. Investigating SOA gain recovery, saturation, and switching capabilities for enhanced network efficiency.
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Optimisation of the Key SOA Parameters for Amplification and Switching By: Supervision Team: Ahmed Abd El Aziz Shalaby Dr. Wai Pang Ng Prof. ZabihGhassemlooy Prof. MoustafaHussien
Proposed core optical router Source / target node Core Network
Introduction All-optical router
Introduction Symetric Mach-Zehnder Interferometer(SMZI)
Research Aim • To design a bi-directional SMZ and implement it in the router to reduce components, time and cost.
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.
Output signals Injection current (I) Output facet L Input facet of active region Input signals SOA structure w H
Segmentisation model of the SOA t=0 t=l/vg t=L/vg Ni input signal output signal N(1) N(5)
Results • Normalised gain response of the SOA with no input signal.
Results Injection of the input pulse • Normalised gain response of the SOA due to the injection of a short input pulse.
Results Injection of the continuous wave • Normalised gain response of the SOA due to the injection of a continuous input signal. Saturation gain
SOA for amplification • Condition: • 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.
SOA for amplification • The output gain corresponding to the input power at different bias currents. • Reference saturation gain: • at I=150mA 66 • at I=200mA 96 • at I=250mA 127
SOA for switching • Condition: • 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.
SOA for switching • The saturation control pulse (CP) for the corresponding input power at different bias currents.
SOA gain recovery • SOA gain dependence on the bias current.
SOA gain recovery Recovery time • Normalised gain response of the SOA due to the injection of a short input pulse.
SOA gain recovery • Normalised gain response of the SOA due to partial increase of the bias current.
SOA gain recovery Partial increase of bias current t=0 t=l/vg t=L/vg Propagating input signal Propagating output signal
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
SOA gain recovery • SOA bit rate due to the additional bias current. SOA bit rate=27.027 Gbps Improvement of: 7.5 times at 95% recovery
SOA gain recovery • Time needed to apply additional bias current. Time needed : 35ps for 90mA 154ps for 10mA
Bi-directional SOA model t=0 t=l/vg t=L/vg Propagating output signal Propagating input signal Co-propagating output signal Co-propagating input signal
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.
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.
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.