h. le-minh, z. ghassemlooy, w.p. ng. and r. ngah optical communication research group
Post on 12-Jan-2016
45 Views
Preview:
DESCRIPTION
TRANSCRIPT
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)
Others Ultrafast Nonlinear Interferometer (UNI) Symmetric Mach-Zehnder (SMZ) …
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)
Others Ultrafast Nonlinear Interferometer (UNI) Symmetric Mach-Zehnder (SMZ) …
All-optical Switches: NOLM
Nonlinear Optical Loop Mirror (NOLM)
CP
50:50
CW CCW
Input port Output port
Reflected portData in
Reflected data
Switched data
Long loop
• Long fibre loop to induce the nonlinearity
• Non-integrated capability
• High control pulse (CP) energy
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
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
Full saturation
Case 3: CP exited the SOA
Fully amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Single Control Pulse
SOA
CW
CCW
Different effects on CW & CCW
Different transitional effects on CW & CCW
Case 3: CP exited the SOA
Fully amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Single Control Pulse
SOA
CW
CCW
2TSOA
Case 3: CP exited the SOA
Fully amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
Dependent on the SOA length
TOAD: Single Control Pulse
SOA
CW
CCW
Case 3: CP exited the SOA
2TSOA
TOAD: Single Control Pulse
SOA
CW
CCW
Issues:
Triangle CW & CCW gain-profiles. Thus Asymmetric switching window!
2TSOA
Case 3: CP exited the SOA
TOAD: Dual Control Pulses
Both control pulses simultaneously excite SOA from both directions.
• Lower inter-channel crosstalk
• Symmetrical switching window profile
CP1
SOA
50:50
CW CCW
Input port Output port
Reflected port
Fibre loop
Data in
Reflected data
Switched data
CP2
TOAD: Dual Control Pulses
Case 1: CP1 and CP2 entering SOA
SOA
CW
CCW
CP1
CP2
Partly amplifiedFully amplified
TOAD: Dual Control Pulses
SOA
CW
CCW
CP1
CP2
CCW data counter-propagate with CP1 will receive partial saturation
CCW data co-propagate with CP2 will receive full saturation
Case 1: CP1 and CP2 entering SOA
SOA
CW
CCW
CP1
CP2
Partly amplifiedFully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Similar effects on CW
Case 1: CP1 and CP2 entering SOA
SOA
CW
CCW
CP1
CP2
Similar effects on CW & CCW
SOA
CW
CCW
CP1
CP2
Partly amplifiedFully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
SOA
CW
CCW
CP1
CP2
Case 2: CP1 and CP2 passing each other within the SOA
At the kth segment of the SOA, where CP2 arrives
Fully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
At the kth segment of the SOA, where CP2 arrives
• CP1 saturates the kth segment and leaves
• The segment-gain begins recovering after CP1 exited
• With the arrival of CP2, the kth segment is forced into saturation
Case 2: CP1 and CP2 passing each other within the SOA
SOA
CW
CCW
CP1
CP2
Fully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
SOA
CW
CCW
CP1
CP2
Case 2: CP1 and CP2 passing each other within the SOA
SOA
CW
CCW
CP1
CP2
Fully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Segment kth may have more gain saturation
Case 2: CP1 and CP2 passing each other within the SOA
SOA
CW
CCW
CP1
CP2
SOA
CW
CCW
CP1
CP2
Fully amplified
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
SOA
CW
CCW
CP1
CP2
Part of TSOA CCW has partial saturation
(A)
CW or CCW gain- profile
Time
(A)
(B)
(C)
G0
(D) GSAT
Case 3: CP1 and CP2 exit the SOA
Fullly amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Part of TSOA CCW has partial saturation
(A)
CW or CCW gain- profile
Time
(A)
(B)
(C)
G0
(D) GSAT
Case 3: CP1 and CP2 exit the SOA
SOA
CW
CCW
CP1
CP2
Part of TSOA CCW has partial saturation + deeper saturation
(C)
Fullly amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Part of TSOA CCW has partial saturation
(A)
Part of TSOA CCW has partial saturation + deeper saturation
(C)
Steep transitionalregion (B)
CW or CCW gain- profile
Time
(A)
(B)
(C)
G0
(D) GSAT
Case 3: CP1 and CP2 exit the SOA
SOA
CW
CCW
CP1
CP2
Fullly amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Steep transitionalregion (B)
CW or CCW gain- profile
Time
(A)
(B)
(C)
G0
(D) GSAT
Case 3: CP1 and CP2 exit the SOA
SOA
CW
CCW
CP1
CP2
Then full saturation
(D)
Part of TSOA CCW has partial saturation + deeper saturation
(C)
Part of TSOA CCW has partial saturation
(A)
Fullly amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
TOAD: Dual Control Pulses
Steep CW & CCW gain-profiles Symmetric switching window
CW & CCW gain- profiles
Time
Case 3: CP1 and CP2 exit the SOA
SOA
CW
CCW
CP1
CP2
Fullly amplifiedFully saturated
Co-propagating saturationCounter-propagating saturation
Simulation Results
Main parameters
Parameters Values
SOA length 500 m
SOA spontaneous lifetime 100 ps
SOA confinement factor 0.3
SOA transparent carrier density 1024 m-3
SOA line-width enhancement 4
SOA active area 3x10-13 m2
SOA differential gain 2x10-20 m2
Number of SOA segments 100
Control pulse width (FWHM) 1 ps
Single control pulse power (PCP) 1 W
Dual control pulse power (PCP1= PCP2)
0.5 W per CP
Asymmetric SOA placement Tasym 2 ps
Simulation Results: Switching window
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
top related