Transcript AN INTERACTIVE ENVIRONMENT FOR SIMULATION AND …

TOAD Switch
with Symmetric Switching Window
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/
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)
• Long
Long loop
CW
CP
• Non-integrated capability
CCW
• High control pulse (CP) energy
50:50
Input port
Data in
Output port
Reflected port
Reflected data
fibre loop to induce the nonlinearity
Switched data
All-optical Switches: TOAD
Terahertz Optical Asymmetric Demultiplexer (TOAD)
SOA
Fibre
loop
• Introduced by P. Prucnal (1993)
• Only Semiconductor Optical Amplifier
(SOA) induces nonlinearity
CW
CP
CCW
• Possible to integrate in chip
50:50
Input port
Data in
Output port
Reflected port
Reflected data
Switched data
• Low control pulse (CP) energy
• High inter-channel crosstalk
• Asymmetrical switching window profile
All-optical Switches: TOAD
Terahertz Optical Asymmetric Demultiplexer (TOAD)
SOA
Fibre
loop
• Introduced by P. Prucnal (1993)
• Only Semiconductor Optical Amplifier
(SOA) induces nonlinearity
CW
CP
CCW
• Possible to integrate in chip
50:50
Input port
Data in
Output port
Reflected port
Reflected data
Switched data
• 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:

1
GTOAD  t   GCW  t   GCCW  t   2 GCW  t  GCCW  t  cos   t 
4

 GCCW t  

 t   ln
2  GCW t  

• 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 SOA
Case 1: No CP
SOA
Fibre
loop
SOA
CW
CCW
CW
CP
CCW
50:50
Input port
Data in
Data propagating in SOA
experience partial-gain
amplification
Output port
Reflected port
Reflected data
Partly amplified
Switched data
TOAD: Single Control Pulse
Effects data CW and CCW components passing through SOA
Case 1: No CP
SOA
SOA
CW
CW
CCW
CCW
Data propagating in SOA
experience partial-gain
amplification
After passing full-length
SOA, data experience fullgain amplification
Partly amplified
Fully amplified
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
Case 2: With CP applied to the SOA in CW direction
SOA
SOA
CW
CW
CCW
CCW
Data will experience full-gain
amplification prior to CP being
applied
Partly amplified
Co-propagating saturation
(Will experience full saturation when data exits SOA)
Fully amplified
Counter-propagating saturation
(Will not experience full saturation when data exits SOA)
TOAD: Single Control Pulse
Case 2: With CP applied to the SOA in CW direction
SOA
SOA
CW
CW
CCW
CCW
Data will experience full-gain
amplification prior to CP being
applied
Data seeing saturated part of
SOA will experience partial
saturation
Partly amplified
Co-propagating saturation
(Will experience full saturation when data exits SOA)
Fully amplified
Counter-propagating saturation
(Will not experience full saturation when data exits SOA)
TOAD: Single Control Pulse
Case 2: With CP applied to the SOA in CW direction
SOA
SOA
CW
CW
CCW
CCW
More saturation
Data well before entering of CP
to SOA will experience full-gain
amplification
Data seeing saturated part of
SOA will experience partial
saturation
Partly amplified
Co-propagating saturation
(Will experience full saturation when data exits SOA)
Fully amplified
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
Part of transitional period
2TSOA is partly saturated
Fully amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Single Control Pulse
Case 3: CP exited the SOA
SOA
CW
CCW
Part of transitional period
2TSOA is partly saturated
Full saturation
Fully amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Single Control Pulse
Case 3: CP exited the SOA
Different
transitional
effects
CW & CCW
Different
effects on
CW &on
CCW
SOA
CW
CCW
Fully amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Single Control Pulse
Case 3: CP exited the SOA
SOA
CW
CCW
2TSOA
Fully amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Single Control Pulse
Case 3: CP exited the SOA
SOA
CW
CCW
2TSOA
 Dependent on the SOA length
TOAD: Single Control Pulse
Case 3: CP exited the SOA
SOA
CW
CCW
2TSOA
Issues:
Triangle CW & CCW gainprofiles. Thus Asymmetric
switching window!
TOAD: Dual Control Pulses
Both control pulses simultaneously excite SOA from both directions.
CP2
SOA
Fibre
loop
• Lower inter-channel crosstalk
• Symmetrical switching window profile
CW
CP1
CCW
50:50
Input port
Data in
Output port
Reflected port
Reflected data
Switched data
TOAD: Dual Control Pulses
Case 1: CP1 and CP2 entering SOA
SOA
CW
CCW
CP1
CP2
Partly amplified
Fully amplified
TOAD: Dual Control Pulses
Case 1: CP1 and CP2 entering SOA
SOA
SOA
CW
CW
CCW
CCW
CP1
CP1
CP2
CP2
CCW data counter-propagate with CP1
will receive partial saturation
CCW data co-propagate with CP2
will receive full saturation
Partly amplified
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 1: CP1 and CP2 entering SOA
Similar
Similar
effects
effects
on CW
on&CW
CCW
SOA
SOA
CW
CW
CCW
CCW
CP1
CP1
CP2
CP2
Partly amplified
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 2: CP1 and CP2 passing each other within the SOA
SOA
CW
CCW
At the kth segment
of the SOA, where
CP2 arrives
CP2
CP1
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 2: CP1 and CP2 passing each other within the SOA
SOA
CW
CCW
At the kth segment
of the SOA, where
CP2 arrives
CP2
CP1
• 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
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 2: CP1 and CP2 passing each other within the SOA
SOA
SOA
CW
CW
CCW
CP2
CCW
CP2
CP1
CP1
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 2: CP1 and CP2 passing each other within the SOA
SOA
SOA
CW
CW
CCW
CP2
CCW
CP2
CP1
CP1
Segment kth may have more gain saturation
Co-propagating saturation
Fully amplified
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 3: CP1 and CP2 exit the SOA
G0
SOA
CW or
CCW
gainprofile
CW
CCW
CP2
CP1
(A)
(B)
(C)
GSAT
(D)
Time
Part of TSOA CCW has
partial saturation
(A )
Fullly amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 3: CP1 and CP2 exit the SOA
G0
SOA
CW or
CCW
gainprofile
CW
CCW
CP2
CP1
Part of TSOA CCW has
partial saturation
(A )
(A)
(B)
(C)
GSAT
(D)
Time
Part of TSOA CCW has
partial saturation +
deeper saturation
(C)
Fullly amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 3: CP1 and CP2 exit the SOA
G0
SOA
CW or
CCW
gainprofile
CW
CCW
CP2
CP1
Part of TSOA CCW has
partial saturation
(A )
Part of TSOA CCW has
partial saturation +
deeper saturation
(C)
(A)
(B)
(C)
GSAT
(D)
Time
Steep transitional
region (B)
Fullly amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 3: CP1 and CP2 exit the SOA
G0
SOA
(A)
CW or
CCW
gainprofile
CW
CCW
(B)
(C)
GSAT
CP2
CP1
Part of TSOA CCW has
partial saturation
(A )
Part of TSOA CCW has
partial saturation +
deeper saturation
(C)
(D)
Time
Steep transitional
region (B)
Then full saturation
(D )
Fullly amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
TOAD: Dual Control Pulses
Case 3: CP1 and CP2 exit the SOA
SOA
CW &
CCW
gainprofiles
CW
CCW
CP2
CP1
Time
Steep CW & CCW gain-profiles  Symmetric switching window
Fullly amplified
Co-propagating saturation
Fully saturated
Counter-propagating saturation
Simulation Results
Main parameters
Parameters
Values
SOA length
500 m
SOA spontaneous lifetime
100 ps
SOA confinement factor
SOA transparent carrier density
SOA line-width enhancement
0.3
1024 m-3
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)
1W
Dual control pulse power (PCP1= PCP2)
Asymmetric SOA placement Tasym
0.5 W per CP
2 ps
Simulation Results: Switching window
Gain profiles and corresponding TOAD switching window
Improved switching window by using dual control pulses
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



CP2 arrives late in
comparison with CP1
Tasym = 2ps
TSOA = 6ps
Impairment of CP1’s and CP2’s arrivals
 Severely bad switching window profiles
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