Single-shot 3D characterization of spatiotemporal wave packets via a spatiotemporal wavefront sensor (STWFS)

The advent of spatiotemporal wave packets (STWPs), represented by spatiotemporal optical vortices (STOVs), has paved the way for the exploration in optics and photonics. To date, despite considerable efforts, a comprehensive and efficient practical means to characterize wave packets with such complex structures is still lacking. In this study, we introduced a method designed to achieve high-precision and high-throughput spatiotemporal wave packet measurements using a user-friendly setup. This method is based on a quadriwave lateral shearing interferometric wavefront sensor that utilizes wavelength division multiplexing, termed the “spatiotemporal wavefront sensor (STWFS).” Using this method, we have fabricated a compact prototype with 295×295 spatial pixels×36 wavelength channels of 0.5 nm spectral resolution in a single frame. This STWFS enabled single-shot self-referenced spatiotemporal three-dimensional (3D) optical field characterizations of STWPs with transverse orbital angular momenta L of 1 and 2 and obtained the dynamic visualization of the focused propagation of STOV pulses. Furthermore, the STWFS provides a 1.87 nm (0.95%) root mean square absolute accuracy for spatiotemporal phase reconstruction. The STWFS exhibits excellent comprehensive performance compared to existing 3D spatiotemporal metrology methods. As a spatiotemporal optical field characterization method, the STWFS can be applied to any type of ultra-short laser beam and offers ultrafast 3D diagnostics, contributing to spatiotemporal photonics and broader applications across different fields such as light–matter interactions and optical communications.