m. f. chiang, z. ghassemlooy, wai pang ng, h. le minh, and v. nwanafio
DESCRIPTION
Crosstalk Investigation of an All-Optical Serial-to-Parallel Converter Based on the SMZ. M. F. Chiang, Z. Ghassemlooy, Wai Pang Ng, H. Le Minh, and V. Nwanafio Optical Communication Research Group Northumbria University, United Kingdom http://soe.unn.ac.uk/ocr/. Contents. Introduction - PowerPoint PPT PresentationTRANSCRIPT
PGNET2006M.F, Chiang
M. F. Chiang, Z. Ghassemlooy, Wai Pang Ng,
H. Le Minh, and V. Nwanafio
Optical Communication Research Group
Northumbria University, United Kingdom
http://soe.unn.ac.uk/ocr/
Crosstalk Investigation of an All-Optical Serial-to-Parallel Converter Based on the
SMZ
PGNET2006M.F, Chiang
Contents
Introduction Semiconductor Optical Amplifier Symmetric Mach-Zehnder (SMZ) Gain Profiles and Switching Window Serial-to-Parallel Converter Crosstalk Results Conclusions
PGNET2006M.F, Chiang
Introduction
There is a growing demand for all optical switches and router at very high speed, to avoid the bottelneck imposed by the electronic switches.
In all-optical packet-switched networks, a Serial-to-Parallel Converter (SPC) is an important element in the header processing unit for address recognition.
SPC based on non-linear all-optical devices, e.g. SOAs, have have non-ideal switching window, thus experiencing residual channel crosstalk.
Here we investiagte a SPC at 80Gb/s investigating its crosstalk characteristics.
PGNET2006M.F, Chiang
Input signals (light)
Carrier density &
SOA gain (XGM)
SOA refractive index &
Induced phase (XPM)
Input signals
P
N
Injection current
SOA
Semiconductor Optical Amplifier (SOA)
PGNET2006M.F, Chiang
0 00 0
( )( )( )
i s
m
Ig N L
g N N Lg L eLwdG e e e
SOA Gain Profile
gm: the material gain, : the optical loss, g0: the gain coefficient, I: the injection current, N: the carrier density at the operating current I, N0: the carrier density at transparency, i: the current injection efficiency, s: the spontaneous recombination lifetime of the carriers, e: the electronic charge, L, w, and d: the length, width, and thickness of the active region of the SOA.
PGNET2006M.F, Chiang
S’(t+π/2)
S’(t)
S’’(t)
S’’’(t)
S’’’(t+π/2)
Pout,1(t)=S’’’(t)+S’’’(t+π/2+π/2)
Pout,2(t)=S’’’(t+π/2)+S’’’(t+π/2)
Pin(t)=S(t)
Signals emerge from output2
S’(t+π/2)
S’(t)
S’’(t)
S’’(t+π/2)
S’’’(t+ π)
S’’’(t+π/2)
Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2)
Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2)
Pin(t)=S(t)
Signals emerge form output1CP1
π
Case 1: Without CP (SMZ is balanced)
Case 2: With CP1 only (SMZ unbalanced) Case 3: With both CP1&CP2
(SMZ is balanced again)
CP2π
Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2 + π)
Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2 + π)
Signals emerge from output2 again
S’’’(t+π/2+ π )
Symmetric Mach-Zehnder (SMZ)Case 1: Without CP (SMZ is balanced)
Case 2: With CP1 only (SMZ unbalanced)
PC2
Output2
Output1
Coupler4
Coupler3
Coupler2
Coupler1
SOA2
SOA1 PBS
PC1
PBSS’’(t+π/2)
PC2
Output2
Output1
Coupler4
Coupler3
Coupler2
Coupler1
SOA2
SOA1 PBS
PC1
PBS
PC 3-dB coupler PBS
PGNET2006M.F, Chiang
out,1 in 1 2 1 2
1( ) ( ) ( ) ( ) 2 ( ) ( ) cos( )
8P t P t G t G t G t G t LEF 1 20.5 ln /G G
Gain Profiles of SOA1&SOA2 and SMZ Switching Window (SW)
Pout,1(t): The power at output1 of SMZ, Pin(t): the power of the input signal, : the phase difference of the input signals between the upper and lower arms of the SMZ,
and LEF: the linewidth enhancement factor.
;
PGNET2006M.F, Chiang
Bit 3 Bit 2 Bit 1 Bit 0
1 x 4 Splitter
3Tb
2Tb
Tb
Bit 0
Bit 1
Bit 2
Bit 3
Tsw
CP1
CP2
Serial-to-Parallel Converter (SPC) - 1
PGNET2006M.F, Chiang
.. .1.. 1.. 0.. 1
Outputparallel
bits
MSB LSB
SOA2
SOA1
CP2
CP1
Tb
2 Tb
3 Tb
1x4 Spliter
0
3
2
1
PC 3-dB couplerFDL
SMZ1
PBS
Inputserialbits
Serial-to-Parallel Converter (SPC) - 2
PGNET2006M.F, Chiang
10 nt t10log /CXT P P
Crosstalk (CXT)
Pnt: sum of the output signal power of all non-target channels and Pt: the output signal power of the target channel.
Switching window
No-target channels
PGNET2006M.F, Chiang
VPI Simulation ParametersSOA
ParametersDefault Values
SOA ParametersDefault Values
Injection current
0.15 ACarrier density at
transparency1.4 x 1024 m-3
Length 500 x 10-6 mLinewidth
enhancement factor4
Width 3 x 10-6 mRecombine constant
A1.43 x 108 s-1
Height 80 x 10-9 mRecombine constant
B1 x 10-16 m3 s-1
Confinement factor
0.15Recombine constant
C3 x 10-41 m6 s-1
Internal losses 40 x 102 m-1 Initial carrier density 3 x 1024 m-3
Differential gain 2.78 x 10-20 m2
System Parameters Default Values
Signal power 1 mW
Control power 20 mW
Tsw 10 ps
FWHM of signal & control pulses 2 ps
Emission wavelength of signal & control pulses
1552.52 nm
Operation bit rate 80 Gb/s
PGNET2006M.F, Chiang
Simulation Results – 1
-21
-20
-19
-18
-17
-16
-15
-14
0 20 40 60 80 100 120 140 160 180 200 220
Control Power (mW)
CX
T R
atio
(d
B)
SP=0.5mW
SP=1mW
SP=2mW
SP=4mW
-19.8
-19.6
-19.4
-19.2
-19
-18.8
-18.6
-18.4
0 0.5 1 1.5 2 2.5 3 3.5
FWHM of CP&SP (ps)
CX
T R
atio
(d
B)
PGNET2006M.F, Chiang
Simulation Results – 2
-29
-27
-25
-23
-21
-19
-17
-15
0 2 4 6 8 10 12 14 16
Tsw (ps)
CX
T R
atio
(d
B)
-20
-19.5
-19
-18.5
-18
-17.5
-17
-16.5
-16
-15.5
0 2 4 6 8 10Linewidth Enhancement Factor
CX
T R
atio
(d
B)
PGNET2006M.F, Chiang
Simulation Results – 3
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0 0.1 0.2 0.3 0.4 0.5 0.6
Inject Current (mA); Confinement Factor
CX
T R
atio
(dB
)
Inject Current
ConfinementFactor
-21
-20
-19
-18
-17
-16
0 200 400 600 800 1000 1200
SOA Length (um)
CX
T R
atio
(d
B)
PGNET2006M.F, Chiang
Simulation Results – 4
SOA Parameters
Optimum Values
System ParametersOptimum
Values
Injection current 0.15 A Signal power 0.5 mW
Length 1000 x 10-6 m Control power 20 mW Confinement
factor0.15 Tsw 3 ps
Linewidth enhancement
factor 0.5
FWHM of signal &
control pulses 1 ps
Operation bit rate SPC Output power CXT
80 Gb/s 2.80 mW – 33.27 dB
160 Gb/s 1.40 mW – 28.20 dB
320 Gb/s 0.47 mW – 22.78 dB
PGNET2006M.F, Chiang
Conclusions
In the SPC,CXT is highly dependent on the gain of the SMZ switching window and the difference in the gain profiles of the SOAs in the gain recovery region.
There is a trade-off between the amount of CXT and the power level of the output signal.
By carefully selecting the SOA parameters the CXT level of the SPC could be further controlled to ensure the optimum performance.
PGNET2006M.F, Chiang
Thank You !
Question, please ?