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Simulation Research On All-Optical Regeneration Of RZ-DQPSK Signals

Posted on:2013-10-23Degree:MasterType:Thesis
Country:ChinaCandidate:X F LiFull Text:PDF
GTID:2248330392457936Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Compared to on-off keying (OOK) modulation format, differential quardrature phaseshift keying (DQPSK) has a higher fiber nonlinear tolerance and chromatic dispersiontolerance, and lager spectral efficiency, has been growing interest in high speed and largecapacity fiber transmission systems. Semiconductor optical amplifier (SOA) is playing aincreasing important role in all-optical processing for its notable advantages whichincludes: high nonlinear coefficient, wide band of operation wavelength, small size, lowdriving power and convenient for integration. In these thesis, noise compressingmechanism of cross-gain compression in SOA is studied theoretically, and we simulateand analyze the all-optical2R (Reamplifying, Reshaping) regeneration performance ofRZ-DQPSK signals based on cascaded SOA in transmission systems through using Matlabsoftware and Optisystem simulation software. The main contribution of this work is asfollows:(1) Theory of wavelength conversion based on cross-gain modulation effect in SOAand physical mechanism of cross-gain compression effect in SOA are studied. The SOAmodel is established, and noise compressing mechanism of cross-gain compression inSOA is analyzed theoretically.(2) Modulation and demodulation method for DQPSK modulation format are studiedand the simulation of process is implemented.(3) We firstly simulate40Gb/s and80Gb/s RZ-DQPSK signals transmission systemswithout regeneration, and then simulate and analyze the regeneration perform oftransmission systems with regeneration. The current of SOA, the power of optical sourceand the delayed time are optimized through simulating for enhanced the regenerationperformance of regenerator. On above conditions, the result of simulation shows that Qfactor of signals with regeneration is enhanced significantly and the eye opening of whichis improved. Finals, we analyze the enhancement of the Q factor in different transmissiondistance between with regeneration and without regeneration. The reason of aboveanalysis decides the regeneration position in transmission system and the longest transmission distance with one regenerate can be obtained. We also study the influence ofthe transmission span which is changed from50km to100km.
Keywords/Search Tags:Differential quardrature phase shift keying, Semiconductor optical amplifiers, All-optical2R regeneration, Cross-gain modulation, Cross-gain compression effect
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