Single-shot ultrafast compressive complex-amplitude imaging of solid surface evolution in picoseconds.

Ultrafast imaging is a powerful approach to study laser-matter interactions with full spatiotemporal resolution in an ultrafast pump-probe scheme. Conventional ultrafast imaging techniques only capture the evolving probe intensity profile without any phase information, allowing indirect interpretation of the physical dynamics of the laser-sample interaction. Here, we demonstrate a single-shot ultrafast imaging technique that captures both the evolving intensity and phase profiles of the probe pulse by combining the spectral compressive imaging technique and the diffractive phase retrieval method. Such a complex-amplitude sensitive ultrafast imaging technique, with extra phase information in addition to intensity and a temporal resolution of ~1 ps, enables comprehensive studies of the picosecond-scale dynamics of femtosecond laser ablation on metal and semiconductor materials, specifically the spallation of the liquid gold surface layer and the phase explosion of the silicon liquid-gas mixture.