Intra-channel nonlinear effects impose a major limitation to system performance in high speed optical transmission.These effects,which are usually referred to intra-channel four-wave mixing(IFWM) and cross-phase modulation(IXPM),may cause amplitude and timing jitter and lead to serious transmission penalties.The paper discussed causes and several factors of intra-channel pulse interaction.Analysis and numerical simulation derive conclusions as follows:To suppress intra-channel nonlinear effects,phase modulation is superior to amplitude modulation,and post-compensation of dispersion is superior to pre-compensation,especially for large launched power.In addition,the duty cycle of pulse has an optimum value for a certain launched power.