Crosstalk Investigation of an All-Optical Serial-to-Parallel Converter Based on the SMZ
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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

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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
Contents Converter Based on the SMZ

  • Introduction

  • Semiconductor Optical Amplifier

  • Symmetric Mach-Zehnder (SMZ)

  • Gain Profiles and Switching Window

  • Serial-to-Parallel Converter

  • Crosstalk

  • Results

  • Conclusions


Introduction Converter Based on the SMZ

  • 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.


Semiconductor Optical Amplifier (SOA) Converter Based on the SMZ

Input signals

Injection current

P

Input signals (light)

Carrier density &

SOA gain (XGM)

N

SOA

SOA refractive index &

Induced phase (XPM)


SOA Gain Profile Converter Based on the SMZ

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.


PC1 Converter Based on the SMZ

PC1

SOA1

SOA1

PBS

PBS

Output1

Output1

Coupler2

Coupler2

Coupler1

Coupler1

Coupler4

Coupler4

Output2

Output2

PC2

PC2

Coupler3

Coupler3

SOA2

SOA2

PBS

PBS

CP1

CP2

PC

3

-

dB coupler

PBS

Symmetric Mach-Zehnder (SMZ)

Case 1: Without CP (SMZ is balanced)

Case 1: Without CP (SMZ is balanced)

Pout,1(t)=S’’’(t)+S’’’(t+π/2+π/2)

S’’(t)

S’(t)

S’’’(t)

Pin(t)=S(t)

S’(t+π/2)

S’’’(t+π/2)

S’’(t+π/2)

Pout,2(t)=S’’’(t+π/2)+S’’’(t+π/2)

Signals emerge from output2

Case 2: With CP1 only (SMZ unbalanced)

Case 3: With both CP1&CP2

(SMZ is balanced again)

Case 2: With CP1 only (SMZ unbalanced)

Signals emerge form output1

S’’(t)

Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2 + π)

Pout,1(t)=S’’’(t + π)+S’’’(t+π/2+π/2)

π

S’(t)

S’’’(t+ π)

Pin(t)=S(t)

S’’(t+π/2)

S’(t+π/2)

π

S’’’(t+π/2+ π )

S’’’(t+π/2)

Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2 + π)

Pout,2(t)=S’’’(t+π/2 + π)+S’’’(t+π/2)

Signals emerge from output2 again


Gain Profiles of SOA1&SOA2 and SMZ Switching Window (SW) Converter Based on the SMZ

;

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.


Serial-to-Parallel Converter (SPC) - 1 Converter Based on the SMZ

Tsw

CP1

3Tb

Bit 0

1 x 4 Splitter

2Tb

Bit 3 Bit 2Bit 1Bit 0

Bit 1

Tb

Bit 2

Bit 3

CP2


Output Converter Based on the SMZ

parallel

bits

CP1

3Tb

SMZ1

SOA1

Input

serial

bits

0

SOA2

2Tb

MSB LSB

1x4 Spliter

1

.. .1.. 1.. 0.. 1

Tb

2

3

CP2

FDL

PC

3-dB coupler

PBS

Serial-to-Parallel Converter (SPC) - 2


No-target channels Converter Based on the SMZ

Crosstalk (CXT)

Switching window

Pnt: sum of the output signal power of all non-target channels and Pt: the output signal power of the target channel.


VPI Simulation Parameters Converter Based on the SMZ


Simulation Results – 1 Converter Based on the SMZ


Simulation Results – 2 Converter Based on the SMZ


Simulation Results – 3 Converter Based on the SMZ


Simulation Results – 4 Converter Based on the SMZ


Conclusions Converter Based on the SMZ

  • 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.


Thank You ! Converter Based on the SMZ

Question, please ?


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