Study On Compensation Method Of Non-linear Loss In CO-OFDM System

In the end of20th Century and the early21th Century, the appearance of the Internetpromotes the global communications industry progress, particularly in recent years due to therapid development of multimedia, the transmission of data communication industry has higherrequirements in the society. The channel capacity and higher transmission rate of the opticalfiber backbone transmission network also provide more challenging requirements for thedevelopment of optical communication technology.This paper presented a high rate CO-OFDM system transmission model, combined withthe coherent light and the OFDM technology in the single channel optical transmissionsystem, mainly discussed the nonlinear damage in the optical channel transmission. It wasfound out that, in the coherent optical OFDM system, there are following characteristic andprogress:This paper firstly discussed the working principle of CO-OFDM system, according to thetheoretical analysis, established the mathematical model of CO-OFDM system combined withthe coherent optical communication theory and the OFDM modulation and demodulationtheory, and determined the various system modules of the CO-OFDM system, Including theRF modulation module, RF to light up conversion system, optical fiber links, optical to RFdown converter system and the RF demodulation module.Secondly, According to themathematical model of CO-OFDM system, establish the basic structure of CO-OFDM system,research the main technology and evaluation system of the CO-OFDM system. The platformis a40Gbit/s CO-OFDM simulation platform built by Optisystem and Matlab simulationsoftware. This paper mainly studied the correct connection of Optisystem and Matlabsimulation software; make sure the normal work and the accuracy.Thirdly, According to thenonlinear Schrodinger (NLS) equation that optical pulse transfer in single-mode fiber,analysis the basic principles of fiber nonlinear damage in optical fiber communication(including stimulated inelastic scattering Kerr effect) as well as the effect of nonlinear damageon CO-OFDM system, verify the effects of optical fiber transmission from SPM (self phasemodulation), XPM (cross phase modulation), FWM (four wave mixing effect), GVD (groupvelocity dispersion) effects and other related effects.Morever, Research around the channeloptical fiber nonlinear damage compensation method of CO-OFDM system. From the pointof optical domain compensation nonlinear damage, the phase conjugated compensationalgorithm of the traditional nonlinear compensation algorithm is applied to CO-OFDMsystem. Verify that the phase conjugated compensation algorithm (OPC) can be effectivelyapplied to CO-OFDM system, and analyze the relationship between Q factor and thetransmission distance in the OPC compensation algorithm.Then, Change the OPC compensation method in the link position, verify that by this method it can improve thenonlinear threshold system as well as the maximum Q factor, and improve the performance ofthe system.Finally, the research results of this study are summarized and the further prospect of thetechnology is also discussed.