H. Le-Minh, Z. Ghassemlooy, W.P. Ng. and R. Ngah Optical Communication Research Group School of Engineering & Technology Northumbria University, Newcastle, UK http://soe.unn.ac.uk/ocr/ TOAD Switch with Symmetric Switching Window London Communications Symposium 2004, Sept. 13 th – 14 th
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H. Le-Minh, Z. Ghassemlooy, W.P. Ng. and R. Ngah Optical Communication Research Group School of Engineering & Technology Northumbria University, Newcastle,
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H. Le-Minh, Z. Ghassemlooy, W.P. Ng. and R. Ngah
Optical Communication Research Group
School of Engineering & Technology
Northumbria University, Newcastle, UK
http://soe.unn.ac.uk/ocr/
TOAD Switch
with Symmetric Switching Window
London Communications Symposium 2004, Sept. 13th – 14th
Outlines
Introduction
All-optical switches
TOAD switch
Simulation Results
Conclusions
Introduction
How to enhance high-capacity optical network?
Introduction
How to enhance high-capacity optical network?
Multiplexing Wavelength Division Multiplexing (WDM) Time Division Multiplexing (TDM)
Introduction
How to enhance high-capacity optical network?
Multiplexing Wavelength Division Multiplexing (WDM) Time Division Multiplexing (TDM)
Removing the O/E/O conversions bottleneck
Introduction
How to enhance high-capacity optical network?
Multiplexing Wavelength Division Multiplexing (WDM) Time Division Multiplexing (TDM)
Removing the O/E/O conversions bottleneck
All optical processing
Introduction
How to enhance high-capacity optical network?
Multiplexing Wavelength Division Multiplexing (WDM) Time Division Multiplexing (TDM)
Removing the O/E/O conversions bottleneck
All optical processing: e.g. OTDM + all-optical switch
All-optical Switches
Mechanism:Exploiting the combination of destructive interferences introduced by nonlinearity element to switch/demultiplex target data
All-optical Switches
Mechanism:Exploiting the combination of destructive interferences introduced by nonlinearity element to switch/demultiplex target data
Configurations: Loop
Nonlinear Optical Loop Mirror (NOLM) Semiconductor Laser Amplifier in a Loop Mirror (SLALOM) Terahertz Optical Asymmetric Demultiplexer (TOAD)
• Only Semiconductor Optical Amplifier (SOA) induces nonlinearity
• Possible to integrate in chip
• Low control pulse (CP) energy
• High inter-channel crosstalk
• Asymmetrical switching window profile
All-optical Switches: TOAD
Terahertz Optical Asymmetric Demultiplexer (TOAD)
CP
SOA
50:50
CW CCW
Input port Output port
Reflected port
Fibreloop
Data in
Reflected data
Switched data
• Introduced by P. Prucnal (1993)
• Only Semiconductor Optical Amplifier (SOA) induces nonlinearity
• Possible to integrate in chip
• Low control pulse (CP) energy
• High inter-channel crosstalk
• Asymmetrical switching window profile
TOAD: Switching Window Profile
It mainly depends on the gains and phase as:
ttGtGtGtGtG CCWCWCCWCWTOAD cos24
1
tG
tGt
CW
CCWln2
• GCW(t) and GCCW(t) are the temporal gain-profiles of CW and CCW data components
• (t) is the temporal phase difference between CW and CCW components
• is the linewidth enhancement factor
TOAD: Single Control Pulse
Effects data CW and CCW components passing through SOACase 1: No CP
SOA
CW
CCW
Data propagating in SOA experience partial-gain amplification
Partly amplified
CP
SOA
50:50
CW CCW
Input port Output port
Reflected port
Fibreloop
Data in
Reflected data
Switched data
TOAD: Single Control Pulse
SOA
CW
CCW
SOA
CW
CCW
Data propagating in SOA experience partial-gain amplification
After passing full-length SOA, data experience full-gain amplification
Partly amplified Fully amplified
Effects data CW and CCW components passing through SOACase 1: No CP
TOAD: Single Control Pulse
Case 2: With CP applied to the SOA in CW direction
SOA
CW
CCW
Partly amplified
Fully amplified
TOAD: Single Control Pulse
SOA
CW
CCW
SOA
CW
CCW
Data will experience full-gain amplification prior to CP being applied
Case 2: With CP applied to the SOA in CW direction
Partly amplified
Fully amplified
Co-propagating saturation (Will experience full saturation when data exits SOA)Counter-propagating saturation (Will not experience full saturation when data exits SOA)
TOAD: Single Control Pulse
SOA
CW
CCW
SOA
CW
CCW
Data will experience full-gain amplification prior to CP being applied
Data seeing saturated part of SOA will experience partial saturation
Case 2: With CP applied to the SOA in CW direction
Partly amplified
Fully amplified
Co-propagating saturation (Will experience full saturation when data exits SOA)Counter-propagating saturation (Will not experience full saturation when data exits SOA)
TOAD: Single Control Pulse
SOA
CW
CCW
SOA
CW
CCW
Data well before entering of CP to SOA will experience full-gain amplification
Data seeing saturated part of SOA will experience partial saturation
More saturation
Case 2: With CP applied to the SOA in CW direction
Partly amplified
Fully amplified
Co-propagating saturation (Will experience full saturation when data exits SOA)Counter-propagating saturation (Will not experience full saturation when data exits SOA)
TOAD: Single Control Pulse
Case 3: CP exited the SOA
SOA
CW
CCW
Fully amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation Part of transitional
period 2TSOA is partly saturated
TOAD: Single Control Pulse
SOA
CW
CCW
Part of transitional period 2TSOA is partly saturated
Improved switching window by using dual control pulses
Gain profiles and corresponding TOAD switching window
Simulation Results: Multiple Switching Windows
Dual control pulses Constant CP power Variable Tasym
TSOA = 6ps
Need optimum power of CPs for each switching interval
Simulation Results: Imperfect dual controls
Different power ratio of CP2/CP1
Tasym = 2ps
Impairment of CP1’s and CP2’s power Asymmetric switching window
Simulation Results: Imperfect dual controls
Impairment of CP1’s and CP2’s arrivals
Severely bad switching window profiles
CP2 arrives late in comparison with CP1
Tasym = 2ps TSOA = 6ps
Conclusions: TOAD with dual controls
Achieved narrow and symmetric switching window, which will result in reduced crosstalk.
The switching window is independent of the SOA length, and only depends on the SOA offset
Promising all-optical switch for future ultra-fast photonic networks
Acknowledgments
The authors would like to thank the Northumbria University for sponsoring this research
Thanks also for my supervisor team for guiding the research and contributing helpful discussions
Thank you
Thank you!
References
[1] J. P. Sokoloff, P. R. Prucnal, I. Glesk, and M. Kane, “A Terahertz optical asymmetric demultiplexer (TOAD)”, IEEE Photon. Technol. Lett., 5 (7), pp.787-790, 1993
[2] M. Eiselt, W. Pieper, and H. G. Weber, ”SLALOM: Semiconductor Laser Amplifier in a Loop Mirror”, IEEE J. Light. Tech. 13 (10), pp. 2099-2112, 1995
[3] G. Swift, Z. Ghassemlooy, A. K. Ray, and J. R. Travis, “Modelling of semiconductor laser amplifier for the terahertz optical asymmetric demultiplexer”, IEE Proc. Circ. Devi. Syst. 145 (2), pp. 61-65, 1998