摘要:
提出了一种测量单次超短激光脉冲波形的三阶相关技术.该技术有别于频率分辨光开关法或自参考光谱相位相干电场重构法,技术上采用级联的方式,借助倍频晶体以及和频晶体的非共线频率转换,将双延迟的三阶强度相关信号转换为对应的二维空间强度分布,通过测量双延迟的二维三阶相关信号,无需测量光谱信息,利用解析方法获得脉冲的时间波形;再将它与对应的光谱相结合,利用Gerchberg-Saxton算法,可以准确获得激光场强的时间特性.该测量技术结构简单、算法简便,既适用于单次超快激光脉冲测量,也适用于高重频测量.
Abstract:
A new triple correlation technique for measuring intensity profile of single-shot ultrashort laser pulse is described. The technique uses two consecutive second-order nonlinear interactions of replicas of the pulse for generating a two-coordinate output intensity distribution that corresponds to a third-order correlation function and offers advantages over the previously techniques such as frequency-resolved optical gating, self-referencing spectral phase interferometry for direct field reconstruction because it requires no additional spectral information to profile the pulses. This intensity distribution is recorded, and the pulse profile can be obtained by analytical calculation. Combining the reconstructed intensity profile with its corresponding optical spectrum, the exact phase variation in time can be recovered with Ger-chberg–Saxton algorithm through an iterative calculation.