Single-shot spatio-spectral coupling characterization of ultrashort laser pulses based on compressive sensing and...

The spatio-temporal coupling effect can temporally and spatially distort the ultrashort laser pulses after focusing, resulting in temporal stretching and decreased power density, and its characterization is of great significance for processes such as light field modulation, and pulse compression, and focusing. A single measurement of the spatio-temporal coupling effect of ultrashort laser pulses is technically challenging. In this paper, a global three-dimensional phase retrieval technique based on lens array and compressive sensing is proposed and applied to the quantitative measurement of spatio-spectral coupling distortion of ultrashort laser pulses. The known amount of pulse-front tilt (PFT) in ultrashort pulses is introduced with a wedge plate, and then compressive sensing is carried out through a deformed CASSI (coded aperture snapshot spectral imaging) system. The grating is the dispersion element of this system. In experiment, this method can fully characterize the spatio-spectral coupling effect of ultrashort laser pulses in a single-shot measurement, with good consistency between theoretical and measured results, which reveals potential applications in the field of ultrafast dynamics.