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description
An Ultrafast with High Contrast Ratio 12 All-optical Switch based on Tri-arm Mach-
Zehnder Employing All-optical Flip-flop
An Ultrafast with High Contrast Ratio 12 All-optical Switch based on Tri-arm Mach-
Zehnder Employing All-optical Flip-flop
H. Le Minh, Z. Ghassemlooy and W. P. NgOptical Communications Research Group
NCRLab, School of CEIS,
Northumbria University, Newcastle, UK
IEEEIEEE ICC 2007 Glasgow, 24-28 June 2007 ICC 2007 Glasgow, 24-28 June 2007
IEEE ICC 07, UK
Presentation OutlinePresentation Outline
1. Optical switches
2. SMZ and Contrast Ratio
3. Tri-arm Mach-Zehnder
4. All-optical flip-flop
5. Results
6. Summary
IEEE ICC 07, UK
IntroductionIntroduction
Edge Router (Ingress/Egress) with 4-bit address XXXX
Core Router
1011
1010 0110
0111
Client Network
Client Network
1001
XXXX
Low-speed packet
Low-speed packet
High-speed packet
Core Network
Optical transparency
• High Bit Rate
• High Throughput
SolutionSolutionUltrafastUltrafast
Switching!Switching!
IEEE ICC 07, UK
Optical SwitchesOptical Switches
MEMSMEMS** (Lucent Tech.)(Lucent Tech.) BubblesBubbles** (Agilent)(Agilent)
TOADTOAD** (Princeton)(Princeton)
SMZSMZ** (Japan)(Japan)
1. Overview1. Overview
Cat.1Cat.1
Large scale (> 1616)
Slow response (s-ms)
Non-optically controlled
Cat.2Cat.2
Small scale (22)
Fast response (fs-ps)
Full-optically controlled• Crosstalk
• Contrast
* Sources: Internet articles & websites
IEEE ICC 07, UK
Symmetric Mach-Zehnder (SMZ)Symmetric Mach-Zehnder (SMZ)
CP1
SOA1
SOA2 CP2
Input Output 1
Output 2
CI CO 0
90
0
9090
00
90
+180+180+180
+180
0
180
0
180180
00
180
+180+180+180
+180
90
90
90
9090
9090
90
+180+180+180
+180
IEEE ICC 07, UK
Symmetric Mach-Zehnder (SMZ)Symmetric Mach-Zehnder (SMZ)
Ideally, all non-target switched signals are zero
CP1
SOA1
SOA2 CP2
Input Output 1
Output 2
CI CO
Non-target Target
ttGtGtGtGtSW 2,121211 cos28
1
ttGtGtGtGtSW 2,121212 cos28
1
tG
tGt LEF
2
12,1 ln
2
1
Practically, non-zero non-target switched signals will penalty the contrast ratio
IEEE ICC 07, UK
SMZ – Contrast RatioSMZ – Contrast Ratio
Switching Contrast Ratios
OP1
OP2
0 5 10 15 20 25 30 35 40-30
-20
-10
0
10
20
30
Power of control signals (dBm)C
Rs
(dB
)
Inter-output CR of OP1/OP
2
Inter-channel CR of OP1
Inter-channel CR of OP2
0 5 10 15 20 25 30 35 40-30
-20
-10
0
10
20
30
Power of control signals (dBm)C
Rs
(dB
)
Inter-output CR of OP1/OP
2
Inter-channel CR of OP1
Inter-channel CR of OP2
A1
A0
B1
B0
Inter-channel CR = A1/A0 , B1/B0
Inter-output CR = A1/B0 , B1/A0
tG
tGt LEF
2
12,1 ln
2
1
SMZ: achieve exact for high CR at OP2
TaMZTaMZ(no need (no need ))
: SOA linewidth enhancement
G1,2: Gain profile in arm 1, 2
IEEE ICC 07, UK
Tri-arm Mach-Zehnder (TaMZ)Tri-arm Mach-Zehnder (TaMZ)
Bias + CS1
SOA1
Ein
SOA2
Broadcast + CS2
Input
Output 1
Output 2
CS1
SOA3
Eo_1
Eo_2
22 coupler 21 combiner 12 splitter 3-dB attenuator
EU
EC
EL
SI0
CI1
CI2
CO1
CO2
Upper interferometer
Lower interferometer
Input
CS1
CS2
Output 2
Output 1
TSW
Bias
CS1 and CS2
Broadcast
Output 1
Output 2
Switching Mode
Broadcast Mode
CS0
2,121121122
1212
111 cos28
1 GGKKGKGKSW
3,223222122223
2212 cos2
8
1 GGKKGKGKSW
No need = for switching!
CS2
Opt. Bias
Input
Output 2
Output 1
Opt. Broadcast
AOFF
CS1
CS0
IEEE ICC 07, UK
All-Optical Flip-FlopAll-Optical Flip-Flop
CW
:(1 –)
Q
FBL
TFBL
SET
RESET
SOA1
SOA2
Optical delay
Attenuator
Polarization Beam Splitter (PBS)
Polarization Controller (PC)
TSW
PCW
St
Rt
PFBL
TFBL
CS0 CS1
AOFF
CS2
Opt. Bias
Input
Output 2
Output 1
Opt. Broadcast
AOFF
CS1
CS0
SMZ-based AOFF
1- Ultrafast (ps-response)2- Multiple control pulses to neglect the FBL
IEEE ICC 07, UK
AOFF OperationAOFF Operation
SET
RESET
IEEE ICC 07, UK
AOFF OperationAOFF Operation
SET
RESET
Leading ripple
Trailing ripple
IEEE ICC 07, UK
VPI Simulation ParametersVPI Simulation Parameters
TABLE I SOA PARAMETERSParameters ValuesInitial gain 24 dBLaser chip length 0.510-3 mActive region width 2.510-6 mActive region thickness 0.0410-6 mSpontaneous emission factor – nsp 2 (NF = 6 dB)SCH confinement factor – 0.56Linewidth enhancement factor – LEF 3.0Initial carrier density 11024 m-3
Transparency carrier density 1.51024 m-3
Group effective index 3.7DC bias current 0.15 A
TABLE II SIMULATION PARAMETERSParameters ValuesInput data bit rate 100 Gbit/sInput date pulse power 0 dBmOptical wavelength 1554 nmOptical pulse width – FWHM 2 psPacket length 2 ns (200 bits)Packet guard band 1.5 nsSwitching window width – TSW 5.5 nsAverage optical continuous wave bias signal – 3 dBmAverage broadcast signal – 6 dBmCS0 pulse peak-power 33 dBmCS1 power 11.7 dBmCS1 factor – 0.98CS2 pulse peak-power 25 dBmAOFF splitting factor – 0.125AOFF PCW 0 dBmAOFF feedback loop delay – TFBL 0.2 ns
IEEE ICC 07, UK
TaMZ Contrast Ratio ResultsTaMZ Contrast Ratio Results
Carrier density of SOA1
Carrier density of SOA2
Carrier density of SOA3
Input
CS0/CS2
CS1 (AOFF Q)
Broadcast signal
Output 1
Output 2
CS0 CS2
Achieved CRs
0 5 10 15 20 25 30 35-10
-5
0
5
10
15
20
25
30
Power of CP1 (dBm)
Con
tras
t rat
ios
(dB
)
CROP12
CROP21
CRCH1
CRCH2
• High CR: ~ 20 dB
• Large input power range
IEEE ICC 07, UK
TaMZ Stability (1)TaMZ Stability (1)
0.35 0.4 0.45 0.5 0.55 0.6 0.6510
15
20
25
30
35
40
Coupling factor of CI1
Con
tras
t ra
tios
(dB
)
CROP12
CROP21
Theoretical CROP12
Theoretical CROP21
CRCH1
CRCH2
Input Imbalance
IEEE ICC 07, UK
TaMZ Stability (2)TaMZ Stability (2)Output Imbalance
0.35 0.4 0.45 0.5 0.55 0.6 0.6510
15
20
25
30
35
40
Coupling factor of CO1
Con
tras
t ra
tios
(dB
)
CROP12
CROP21
Theoretical CROP21
CRCH1
CRCH2
Fluctuation in output coupling ratio induce less CR degrading in comparison to input coupling ratio
IEEE ICC 07, UK
SummarySummary
• 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)
IEEE ICC 07, UK
Thank you!