Analysis Of Suppression Method Of Nonlinearities In High-speed Optical Communication System

With the development of technology, there is a continuously increase in transmission capacity and distance of optical fiber communication, which meets the demand of the people on aspects of vast stores of information and the connection all over the world. With the increase of system capacity, nonlinear effects tend to be the major factor to limit the performance of optical fiber communication system. As one of the significant nonlinear effects, Four-wave mixing(FWM) effect brings about power loss of pump signal, meanwhile new frequencies which lead to nonlinear crosstalk of the system. FWM noise is the main source of nonlinear crosstalk of both dense wavelength division multiplexing(DWDM) and orthogonal frequency division multiplexing(OFDM) optical fiber transmission system. Evaluation of the FWM impact on system performance is very important for optimization design of transmission link.This dissertation reviews and develops several analysis methods which focus on the influences of dispersion management, optical phase conjugation(OPC) technology and incident light polarization state on FWM noises for both DWDM and OFDM systems. The main works are given as follows:1. This dissertation reviews the theoretical models of the influence of OPC module on FWM efficiency of OFDM system, and the influence of the incident light polarization states on FWM light intensity.2. Based on Opti System software platform, this dissertation gives a nonlinear separation model,which could numerically assess the effect of FWM noise on the system performance effectively.Meanwhile, the model has been applied to a new kind of dispersion map for the large-capacity transmission. With the model, we simulate the FWM noise for 33 channels of co-polarization DWDM system. The simulations have been carried out for two kinds of modulation schemes: one uses differential phase shift keying(DPSK) modulation for all the channels; the other uses on-off keying(OOK) modulation and DPSK modulation for odd and even channels respectively.3. Based on the nonlinear separation model mentioned above, we also numerically analysis the effects of FWM noise and total nonlinear tolerance for 33 channels of non co-polarization DWDM system. The effects of relative polarization angles between adjacent channels are numerically given with the nonlinear separation model for a kind of new dispersion maps with different dispersion compensation ratios per span.