用改进型空间编码 SPIDER 系统测量复杂脉冲的准确性分析

摘要

与现有多种 SPIDER 装置相比，提出的改进型空间编码 SPIDER 系统在测量结构复杂的超短脉冲方面具有优势。借助数值模拟，以两个不同结构的复杂脉冲为对象，分析准单色辅助脉冲的带宽和频谱位置等因素对该系统测量复杂脉冲的准确度的影响。模拟结果表明，两个复杂脉冲相位重构的误差都将随辅助脉冲准单色带宽的增大而增大，但误差的增幅则有较大差别：含有多种高阶色散但光谱分布和光谱相位曲线都较为平滑的复杂脉冲的误差增幅相对较小；而光谱和相位曲线中存在陡变结构的复杂脉冲则会有较大误差增幅。尤其是当其中一个辅助脉冲的频率刚好选在待测脉冲相位陡变的位置附近时，就容易出现明显的误差。采用多个剪切量测量同一复杂脉冲有助于发现并剔除这样的误差从而提高准确性。%Compared to other SPIDER devices,the modified spatial-encoded-arrangement for SPIDER system (MSEA-SPIDER)are more advantageous for complex pulse measurement.Using two test pulses with different complex features as examples,the affects of the bandwidths and the spectral positions of the two quasi-monochromic auxiliary pulses on the accuracy of characterization of complex pulses are studied by means of numerical simulation.The simulation results show that both the errors of phase reconstruction for these complex pulses increase with the bandwidth enlargement of the auxiliary pulses,but their de-grees of error increase are quite different.The error increases less for the complex pulse with multi-high-order dispersions but smooth profiles of spectral intensity and phase,while much larger for the complex pulse with abrupt variations in its spectral intensity and phase.Especially,when one of the frequencies of the auxiliary pulses is set near each spectral position of the abrupt variations in the pulse phase,the error of phase retrieval should be significantly large.Multi-shearing measurement for the same complex test pulse is helpful to find and remove this kind of error to reach higher accuracy.