液晶空间光调制器的离散型相位调制和像素间隙是4f脉冲整形系统的主要失真原因，基于以上因素的分析，建立了完善的4f脉冲整形系统数学模型，数值模拟了不同相位调制变化率、不同像元尺寸、不同间隙尺寸以及不同色散关系下的离散型相位调制和像素间隙导致的失真情况。模拟结果表明：离散型相位调制会导致整形脉冲中出现副本脉冲，相位调制变化率越大或像元尺寸越大均会导致这种副本脉冲越强，输出目标脉冲失真越严重；像素间隙也会导致整形脉冲中出现副本脉冲，间隙尺寸越大会导致这种副本脉冲越强，输出目标脉冲失真越严重；两种副本脉冲均呈等间隔分布，其周期由每个像元对应的频谱宽度决定，非线性光谱色散会使副本脉冲啁啾化且强度变小。

The discrete step-type phase modulation and pixel gaps of liquid crystal spatial light modulator (LC-SLM) are the main distortion reasons for the 4f pulse shaping system. Based on the analysis of the above factors, the 4f pulse shaping system mathematical model is established and simulated with different modulation rates, different pixel sizes, different gap sizes and different dispersion relations. The simulation results show that step-type phase modulation can lead to replica pulses, the modulation rate or pixel size is larger, the intensity of the replica pulses is stronger, and the distortion of shaped pulse is more serious; the pixel gaps can also lead to replica pulses, the gap size is larger, the intensity of the replica pulses is stronger, and the distortion of shaped pulse is more serious. The interval of the replica pulses is a constant determined by the frequency separation of adjacent pixels. The nonlinear spectral dispersion can reduce the intensity while causing chirp effect of replica pulses.