Borot Antonin, Quéré Fabien
Opt Express. 2018 Oct 1;26(20):26444-26461. doi: 10.1364/OE.26.026444.
The complete characterization of an ultrashort laser beam ultimately requires the determination of its spatio-temporal electric field E(x, y, t), or its spatio-spectral counterpart Ẽ(x, y, ω). We describe a new measurement technique called INSIGHT, which determines Ẽ(x, y, ω), up to an unknown spatially-homogeneous spectral phase. Combining this information with a temporal measurement at a single point of the beam then enables the determination of the spatio-temporal field E(x, y, t). This technique is based on the combination of spatially-resolved Fourier-transform spectroscopy with an alternate-projection phase-retrieval algorithm. It can be applied to any reproducible laser source with a repetition rate higher than about 0.1 Hz, relies on a very simple device, does not require any reference beam, and circumvents the difficulty associated with the manipulation of large beam diameters by working in the vicinity of the beam focus. We demonstrate INSIGHT on a 100 TW-25 fs laser, and use the measurement results to introduce new representations for the analysis of spatio-temporal/spectral couplings of ultrashort lasers.
要全面表征超短激光束，最终需要确定其时空电场E(x, y, t)，或其时空谱对应物Ẽ(x, y, ω)。我们描述了一种名为INSIGHT的新测量技术，它可以确定Ẽ(x, y, ω)，但存在一个未知的空间均匀光谱相位。将此信息与光束单点的时间测量相结合，便可确定时空场E(x, y, t)。该技术基于空间分辨傅里叶变换光谱学与交替投影相位恢复算法的结合。它可应用于任何重复频率高于约0.1 Hz的可重复激光源，依赖于一个非常简单的装置，不需要任何参考光束，并且通过在光束焦点附近工作，避免了与大光束直径操作相关的困难。我们在一台100 TW - 25 fs的激光器上演示了INSIGHT，并利用测量结果引入了用于分析超短激光时空/光谱耦合的新表示方法。
