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M. F. Chiang 1 , Z. Ghassemlooy 1 , W. P. Ng 1 , and H. Le Minh 2

Simulation of an All-Optical 1  2 SMZ Switch with a High Contrast Ratio. M. F. Chiang 1 , Z. Ghassemlooy 1 , W. P. Ng 1 , and H. Le Minh 2 1. Optical Communications Research Group School of Computing, Engineering and Information Sciences Northumbria University, Newcastle upon Tyne, UK

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M. F. Chiang 1 , Z. Ghassemlooy 1 , W. P. Ng 1 , and H. Le Minh 2

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  1. Simulation of an All-Optical 12 SMZ Switch with a High Contrast Ratio M. F. Chiang1, Z. Ghassemlooy1,W. P. Ng1, and H. Le Minh2 1. Optical Communications Research Group School of Computing, Engineering and Information Sciences Northumbria University, Newcastle upon Tyne, UK 2. Department of Engineering Science, University of Oxford, UK http://soe.unn.ac.uk/ocr/

  2. Contents • Introduction • Symmetric Mach-Zehnder (SMZ) • Optical inverter based on SMZ • All-Optical 12 SMZ Switch with a High Contrast Ratio • Simulation Results • Conclusions

  3. Introduction- Research Aim • There is a growing demand for all optical switches and router at very high speed, to avoid the bottleneck imposed by the electronic switches. • All-optical switches, such as SMZs are the key components adopted for switching and routing due to their ultrafast switching time (pico- to sub-picoseconds). However, SMZs have low inter-output CR (< 10 dB). • It is essential to have a high inter-output CR switch for lower value of output crosstalk (CXT).

  4. Introduction All-Optical Switches TOAD UNI Ref: www.iqe.ethz.ch/photonics Ref:(Princeton) SMZ Ref:(Japan)

  5. Symmetric Mach-Zehnder (SMZ)

  6. Semiconductor Optical Amplifier (SOA) Input signals Injection current P Input signals (light) Carrier density & SOA gain (XGM) N SOA SOA refractive index & Induced phase (XPM)

  7. Undesired signal Symmetric Mach-Zehnder (SMZ) • Advantages: • narrow and square switching window • compact size • thermal stability and low power operation Drawback: 1. low inter-output CR (< 10 dB) due to the problem of maintaining the same phase shift.

  8. PC1 PC1 SOA1 SOA1 PBS PBS Output1 Output1 Coupler2 Coupler2 Coupler1 Coupler1 Coupler4 Coupler4 Output2 Output2 PC2 PC2 Coupler3 Coupler3 SOA2 SOA2 PBS PBS CP1 CP2 PC 3 - dB coupler PBS Symmetric Mach-Zehnder (SMZ) Case 1: Without CP (SMZ is balanced) Case 1: Without CP (SMZ is balanced) Pout,1(t)=S’’’(t)+S’’’(t+π/2+π/2) S’’(t) S’(t) S’’’(t) Pin(t)=S(t) S’(t+π/2) S’’’(t+π/2) S’’(t+π/2) Pout,2(t)=S’’’(t+π/2)+S’’’(t+π/2) Signals emerge from output2 Case 2: With CP1 only (SMZ unbalanced) Case 3: With both CP1&CP2 (SMZ is balanced again) Case 2: With CP1 only (SMZ unbalanced) Signals emerge form output1 S’’(t) Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2 + π) Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2) π S’(t) S’’’(t+ π) Pin(t)=S(t) S’’(t+π/2) S’(t+π/2) π S’’’(t+π/2+ π ) S’’’(t+π/2) Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2 + π) Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2) Signals emerge from output2 again

  9. Inter-output Contrast Ratio (CR) of a 12 Switch • The inter-output CR of a 1×2 switch is defined as the power ratio between the switched and non-switched signals at outputsij where i, j = 1 or 2. Typically the value of inter-output CR observed at the SMZ output 2 (CR21) is less than 10 dB. • Here we propose a 1×2 switch utilizing an optical inverter that offers improved CR21.

  10. low inter-output CR (< 10 dB) Improved CR (> 32 dB) All-Optical 12 SMZ Switch with a High Contrast Ratio CEM: clock extraction module

  11. CP (CLK) 1 SOA Output (A bar) Input (CLK) SOA CP (A) 2 All-optical Inverter Based on SMZ

  12. Simulation Results-Simulation Parameter Simulation Tool: Virtual Photonic Inc. (VPI) TABLE II SIGNAL AND CONTROL PULSES DEFAULT PARAMETERS TABLE I SOA SIMULATION PARAMETER

  13. Simulation Results-Time Waveforms Input packets Control pulse Output1 Output2 Output waveforms observed at the proposed 12 switch

  14. Simulation Results-Time Waveforms CR (< 10 dB) The improved CR (> 30 dB) Output CR ratio observed at the proposed 12 switch

  15. Simulation Results- The contrast ratio (CR) against the input packet power

  16. Simulation Results- The contrast ratio (CR) against the control pulse power

  17. Conclusion • The advantages and drawbacks of SMZs were introduced. • The principle of the proposed all-optical 12 SMZ switch with a high contrast ratio was explained. • By carefully selecting the power of the control pulses, inter-output CR of > 32 dB was achieved over a wide range of input packet power (12 dB). • The proposed 12 switch offered an improvement in the inter-output CR of ~ 25 dB in comparison with a single SMZ switch. The proposed switch could potentially be adopted for high-speed signal processing and packet routing in all-optical networks.

  18. Special Thanks for Prof. Z. Ghassemlooy Dr. Wai Pang Ng Dr. Hoa Le Minh All colleagues in NCRLab & Your Attention

  19. Thank you for your kind attention. Questions/Suggestions/Comments, please

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