razali ngah, and zabih ghassemlooy optical communication research group
DESCRIPTION
The Performance of An OTDM Demultiplexer Based on SMZ Switch. Razali Ngah, and Zabih Ghassemlooy Optical Communication Research Group School of Engineering & Technology Northumbria University, United Kingdom http: soe.unn.ac.uk/ocr/. Contents. Introduction OTDM All optical switches - PowerPoint PPT PresentationTRANSCRIPT
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Razali Ngah, and Zabih Ghassemlooy
Optical Communication Research Group
School of Engineering & Technology
Northumbria University, United Kingdom
http: soe.unn.ac.uk/ocr/
The Performance of An OTDM Demultiplexer Based on SMZ Switch
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Contents
Introduction OTDM All optical switches Simulations and results Conclusions
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Introduction
Solution: All optical transmission, multiplexing, switching, processing, etc.
Multiplexing:- To extend a transmission capacity
Electrical
Optical
Drawbacks with Electrical: Speed limitation beyond 40 Gb/s (80 Gb/s future) of:
Electo-optics/opto-electronics devices High power and low noise amplifiers
Bandwidth bottleneck due to optical-electronic-optical conversion
Ch2 M U X
Ch1
ChN
Ch1
D E M U X
ChN
Ch2
Ch2 M U X
Ch1
ChN
Ch1
D E M U X
ChN
Ch2
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Multiplexing - Optical
Wavelength division multiplexing (WDM)
Optical time division multiplexing (OTDM) Hybrid WDM-OTDM
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The total capacity of single-channel OTDM network = DWDM Overcomes non-linear effects associated with WDM:
(i) Self Phase Modulation (SPM) – The signal intensity of a given channel modulates its own refractive index, and therefore its phase
(ii) Cross Phase Modulation (XPM) – In multi-channel systems, other interfering channels also modulate the refractive index of the desired channel and therefore its phase
(iii) Four Wave Mixing (FWM) – Intermodulation products between the WDM channels, as the nonlinearity is quadratic with electric field
Less complex end node equipment (single-channel Vs. multi-channels) Can operate at both:
1500 nm 1300 nm
OTDM
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OTDM - Principle of Operation
Multiplexing is sequential, and could be carried out in: A bit-by-bit basis (bit interleaving) A packet-by-packet basis (packet interleaving)
Clock
ReceiverTransmitter
Clockrecovery
LightsourceLight
source
Data (10 Gb/s)
N
Networknode
Networknode
Drop Add
Rx
Rx
Rx
10 GHzN*10 Gb/s
Data (10 Gb/s)
OTDM DEMUXOTDM MUXAmplifierModulatorsFibre delay line
Fibre
Span
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All Optical Switches
Control pulse
Data in Data out
Coupler
CW CCW
Long fibre loop
Port 1 Port 2
Control coupler
PC
x
Data In s
Data out
Coupler
SLA
CW CCW
Fibre loop
Control Pulse c
PC
Non-linear Optical Loop Mirror (NOLM)Terahertz Optical Asymmetric Demultiplexer
(TOAD)
Requires high control pulse energy and long fiber loop
Asymmetrical switching window profile due to the counter-propagating nature of the data signals
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All Optical Switches – contd.
Symmetric Mach-Zehnder (SMZ)
Symmetrical switching window profile Integratable structure
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All Optical Switches – contd.
Device SwitchingTime
RepetitionRate(GHz)
Noise Figure(dB)
Ease of Integration
?
Practicality
SMZ < 1 ps 100+ GHz 6 YES HIGH
TOAD < 1 ps 100+ GHz 6 YES MEDIUM
NOLM 0.8 ps 100+ GHz 0 NO LOW
UNI < 1 ps 100+ GHz 6 NO MEDIUM
Comparative study of all optical switches [Prucnal’01]
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3 dBCoupler
Tdelay
OTDM Signal Pulses
Control Pulse (switch-on)
Optical filter
Control Pulse (switch-off)
SOA1
SOA2
Output Port 1
SMZ Switch: Principle
3 dBCoupler
OTDM Signal Pulses
Control Pulse Input Port 1
Control Pulse Input Port 2
SOA1
SOA2
Output Port 2
(i) No control pulses
(ii) With control pulses
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SMZ : Switching Window
)(cos.)()(2)()(4
1)( 2121 ttGtGtGtGtW
40 45 50 55 60 65 70 75 80 85 902
4
6
8
10
12
14
16
18
20
Gain Profile of Gc1(__) and Gc2(--)
Time (ps)
Gain
40 45 50 55 60 65 70 750
5
10
15
20
25SMZ switching window
Time (ps)
SM
Z g
ain
G1 and G2 are the gains profile of the data signal at the output of the SOA1 and
SOA2, ΔФ is the phase difference between the data signals, and LEF is linewidth enhancement factor
)/ln(5.0 21 GGLEF
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SMZ : Switching Window (simulation)
TABLE I. SIMULATION PARAMETERSParameter ValueSOA. LengthLSOA 0.3 mm. Active area, 3.0x10-13 m2
. Transparent carrier density, No
1.0x1024 m-3
. Confinement factor, 0.15
. Differential gain, g 2.78x1020 m2
. Linewidth enhancement, 4.0
. Recombination coefficient A1.43x108 1/s. Recombination coefficient B1.0x10-16 m3/s. Recombination coefficient C3.0x10-41 m6/s. Initial carrier density 2.8x1024 m-3
. Total number of segments 50Data and control pulses. Wavelength of control & data 1550 nm. Pulse FWHM 2 ps. Control pulse peak power 1.2 W. Data pulse peak power 2.5 µW
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SMZ : Switching Window (comparison)
45 50 55 60 65 70 750
5
10
15
20
SMZ switching window (Cross)
Time (ps)
SM
Z ga
in
2.025 2.03 2.035 2.04 2.045 2.05 2.055 2.06
x 10-9
5
10
15
20
Time (s)
SM
Z G
ain
SMZ Switching Window
Theoretical Simulation
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The ratio of the output power in the on-state to the output power in the off-state
SMZ : On-Off Ratio
Input signal of the SMZ Transmitted output of the SMZ
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SMZ : On-Off Ratio – contd.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
Linewidth enhancement factor
On
-off
ra
tio
(d
B)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
No
rma
lise
d t
ran
sm
issio
n p
ow
er
0
2
4
6
8
10
12
14
16
18
20
10 40 80 100 160
Bit rate (Gb/s)
On
-off
ra
tio
(d
B)
On-off ratio and normarlised transmission powerAgainst linewidth enhancement factor
On-off ratio at different data rate
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SMZ : BER Performance
___________________________________Parameter Value
Pre-amplifierMode Gain controlledNoise Figure 4 dBGain 25 dB
PIN detector Responsivity 1 A/WThermal noise 10 pA/Hz1/2
Cutoff frequency 7.0x109 Hz__________________________________________
Receiver parameters
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SMZ : BER Performance – contd.
-44 -42 -40 -38 -36 -3410
-20
10-18
10-16
10-14
10-12
10-10
10-8
10-6
10-4
10-2
100
Received power (dBm)
BE
R
back-to-back 10Gb/sSMZ 4x10Gb/s SMZ 8x10 Gb/s SMZ 16x10 Gb/s
BER against the average received power for (a) back-to-back without demultiplexer, (b) 40 – 10 Gb/s demultiplexer, (c) 80 – 10 Gb/s demultiplexer and (d) 160 – 10 Gb/s demultiplexer
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SMZ : BER Performance – contd.
Ngah’04 Tekin’02
IWC4
Diez’00
Elec. Lett
Hess’98
PTL
Jahn’95
Elec. lett
Back-to-back
(10 Gb/s)
Sensitivity
-38 dBm
-35 dBm
-35 dBm
-34 dBm
-37 dBm
40-10 Gb/s
demux.
Power penalty1.2 dB NA NA 0 dB 2.5 dB
80-10 Gb/s
demux.
Power penalty1.4 dB 1 dB 1.2 dB 4 dB NA
160-10 Gb/s
demux.
Power penalty1.5 dB 3.5 dB 2.8 dB NA NA
Comparison with experimental results
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Application of SMZ switch: 1x2 All OTDM Router
Port 1
Port2
SMZ1 (clock
extract)
SMZ2 (read
address)
SMZ3 (route
payload )
( a)
( b)
( c) (e)
(d)
(f)
(a) OTDM Signal
(b) Extracted Clock
(c) Address + Payload
(d) Address
(e) Payload
(f) Payload
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Conclusions
An all optical demultiplexer based on SMZ has been implemented in a simulation environment using VPI.
BER analysis has been performed. The power penalty of the demultiplexer is mainly
due to the ASE noise in the SOAs of the SMZ. The application of low noise SOA will reduce the
power penalty.
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Acknowledgement
Thanks to the University of Teknologi Malaysia for sponsoring the research.
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THANK YOU