Bulk lateral shearing interferometry for spatiotemporal study of time-varying ultrashort optical vortices

The spatiotemporal measurement of ultrashort laser beams usually involves techniques with complex set-ups or limited by instabilities that are unable to accurately retrieve the frequency-resolved wavefront. Here, we solve these drawbacks by implementing a simple, compact, and ultra-stable spatiotemporal characterization technique based on bulk lateral shearing spectral interferometry using a birefringent uniaxial crystal. We apply it to retrieve complex spatiotemporal structures by characterizing ultrafast optical vortices with constant and time-varying orbital angular momentum. This technique can operate in all the transparency range of the anisotropic elements, enabling the characterization in different spectral ranges like infrared, visible, or ultraviolet. (C) 2022 Chinese Laser Press