1. An Ultrafast with High Contrast Ratio 1  2 All-optical Switch based on Tri-arm Mach- Zehnder Employing All-optical Flip-flop H. Le Minh, Z. Ghassemlooy and W. P. Ng Optical Communications Research Group NCRLab, School of CEIS, Northumbria University, Newcastle, UK IEEE ICC 2007 Glasgow, 24-28 June 2007

2. IEEE ICC 07, UK Presentation Outline 1.Optical switches 2.SMZ and Contrast Ratio 3.Tri-arm Mach-Zehnder 4.All-optical flip-flop 5.Results 6.Summary

3. IEEE ICC 07, UK Introduction Optical transparency High Bit Rate High Throughput SolutionUltrafastSwitching!

4. IEEE ICC 07, UK Optical Switches MEMS * (Lucent Tech.) Bubbles * (Agilent) TOAD * (Princeton) SMZ * (Japan) 1. Overview Cat.1 Large scale (> 16  16) Slow response (  s-ms) Non-optically controlled Cat.2 Small scale (2  2) Fast response (fs-ps) Full-optically controlled Crosstalk Contrast * Sources: Internet articles & websites

5. IEEE ICC 07, UK Symmetric Mach-Zehnder (SMZ) 0 90 0 0 0 +180 0 180 0 0 0 +180 90 +180

6. IEEE ICC 07, UK Symmetric Mach-Zehnder (SMZ) Ideally, all non- target switched signals are zero Non-targetTarget Practically, non-zero non-target switched signals will penalty the contrast ratio

7. IEEE ICC 07, UK SMZ – Contrast Ratio Switching Contrast Ratios OP1 OP2 A1A1 A0A0 B1B1 B0B0 Inter-channel CR = A 1 /A 0, B 1 /B 0 Inter-output CR = A 1 /B 0, B 1 /A 0 SMZ: achieve exact  for high CR at OP 2 TaMZ (no need  )  : SOA linewidth enhancement G 1,2 : Gain profile in arm 1, 2

8. IEEE ICC 07, UK Tri-arm Mach-Zehnder (TaMZ) No need  =  for switching!

9. IEEE ICC 07, UK All-Optical Flip-Flop SMZ-based AOFF 1- Ultrafast (ps-response) 2- Multiple control pulses to neglect the FBL

10. IEEE ICC 07, UK AOFF Operation

11. IEEE ICC 07, UK AOFF Operation

12. IEEE ICC 07, UK VPI Simulation Parameters TABLE I SOA PARAMETERS Parameters Values Initial gain 24 dB Laser chip length 0.5  10 -3 m Active region width 2.5  10 -6 m Active region thickness 0.04  10 -6 m Spontaneous emission factor – n sp 2 (NF = 6 dB) SCH confinement factor –  0.56 Linewidth enhancement factor –  LEF 3.0 Initial carrier density 1  10 24 m -3 Transparency carrier density 1.5  10 24 m -3 Group effective index 3.7 DC bias current 0.15 A TABLE II SIMULATION PARAMETERS Parameters Values Input data bit rate 100 Gbit/s Input date pulse power 0 dBm Optical wavelength 1554 nm Optical pulse width – FWHM 2 ps Packet length 2 ns (200 bits) Packet guard band 1.5 ns Switching window width – TSW 5.5 ns Average optical continuous wave bias signal – 3 dBm Average broadcast signal – 6 dBm CS0 pulse peak-power 33 dBm CS1 power 11.7 dBm CS1 factor –  0.98 CS2 pulse peak-power 25 dBm AOFF splitting factor –  0.125 AOFF PCW 0 dBm AOFF feedback loop delay – TFBL 0.2 ns

13. IEEE ICC 07, UK TaMZ Contrast Ratio Results Achieved CRs High CR: ~ 20 dB Large input power range

14. IEEE ICC 07, UK TaMZ Stability (1) Input Imbalance

15. IEEE ICC 07, UK TaMZ Stability (2) Output Imbalance Fluctuation in output coupling ratio induce less CR degrading in comparison to input coupling ratio

16. IEEE ICC 07, UK Summary SMZ and TaMZ are ultrafast switches, however, TaMZ offers better switching contrast ratio (~ 20 dB) in a much larger input power range TaMZ switch provides the blocking and broadcasting capabilities Compact size (possibly integrated)

17. IEEE ICC 07, UK Thank you!