Cover story: Meng YZ, Lu Y, Zhang PF et al. High-frequency enhanced ultrafast compressed active photography. Opto-Electron Adv 8, 240180 (2025)

Single-shot ultrafast compressed imaging (UCI) is an effective tool for studying ultrafast dynamics in physics, chemistry, or material science because of its excellent high frame rate and large frame number. However, the random code used in traditional UCI will lead to low-frequency noise covering high-frequency information due to its uneven sampling interval, which is a great challenge in the fidelity of large-frame reconstruction. Recently, Professor Feng Chen's research group of Xi'an Jiaotong University proposed a high-frequency enhanced ultrafast compressed photography (H-CAP) method. This method projects the microscopic ultrafast phenomenon onto a special coding in the spatial domain, and skillfully extracts the high-frequency information of the microscopic ultrafast phenomenon, which solves the problem of high-frequency information blurring caused by traditional ultrafast compressed imaging. The team successfully use this method to the spatial-temporal characterization of double-pulse induced silicon surface ablation dynamics, which is performed within 220 frames in a single-shot of 300 ps. The reconstructed results not only reflect the change of plasma density during the interaction between laser and material, but also provide insights to the change of material state. This research work provides a new method to observe the ultrafast process with high space-time complexity under a large number of frames. It is expected to become a new method for non-repeatable dynamic processes such as ultrafast laser-matter interaction, ultrafast light field measurement or ultrafast demagnetization.