Crosstalk Investigation of an All-Optical Serial-to-Parallel Converter Based on the SMZ
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M. F. Chiang, Z. Ghassemlooy, Wai Pang Ng, H. Le Minh, and V. Nwanafio PowerPoint PPT Presentation


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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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M. F. Chiang, Z. Ghassemlooy, Wai Pang Ng, H. Le Minh, and V. Nwanafio

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M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

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

  • Introduction

  • Semiconductor Optical Amplifier

  • Symmetric Mach-Zehnder (SMZ)

  • Gain Profiles and Switching Window

  • Serial-to-Parallel Converter

  • Crosstalk

  • Results

  • Conclusions


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

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.


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Semiconductor Optical Amplifier (SOA)

Input signals

Injection current

P

Input signals (light)

Carrier density &

SOA gain (XGM)

N

SOA

SOA refractive index &

Induced phase (XPM)


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

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.


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

PC1

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


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

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.


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Serial-to-Parallel Converter (SPC) - 1

Tsw

CP1

3Tb

Bit 0

1 x 4 Splitter

2Tb

Bit 3 Bit 2Bit 1Bit 0

Bit 1

Tb

Bit 2

Bit 3

CP2


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Output

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


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

No-target channels

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.


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

VPI Simulation Parameters


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Simulation Results – 1


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Simulation Results – 2


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Simulation Results – 3


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Simulation Results – 4


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

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.


M f chiang z ghassemlooy wai pang ng h le minh and v nwanafio

Thank You !

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