Ultrafast dynamics observation during femtosecond laser-material interaction

TLDR

Femtosecond laser technology attracts attention for its unique laser‑material interaction mechanisms, yet extreme nonequilibrium conditions raise fundamental questions about material removal and pose challenges in temporal, spatial, and panoramic measurement resolutions. The review surveys cutting‑edge ultrafast dynamic observation techniques—time‑resolved pump‑probe shadowgraphy, ultrafast continuous optical imaging, and 4D ultrafast SEM—to investigate these fundamental questions. It details each technique’s basic principle, representative applications in laser‑material interaction, and strengths and limitations. The review discusses prospects for technical advancement in ultrafast dynamic observation of femtosecond laser‑material interaction.

Abstract

Abstract Femtosecond laser technology has attracted significant attention from the viewpoints of fundamental and application; especially femtosecond laser processing materials present the unique mechanism of laser-material interaction. Under the extreme nonequilibrium conditions imposed by femtosecond laser irradiation, many fundamental questions concerning the physical origin of the material removal process remain unanswered. In this review, cutting-edge ultrafast dynamic observation techniques for investigating the fundamental questions, including time-resolved pump-probe shadowgraphy, ultrafast continuous optical imaging, and four-dimensional ultrafast scanning electron microscopy, are comprehensively surveyed. Each technique is described in depth, beginning with its basic principle, followed by a description of its representative applications in laser-material interaction and its strengths and limitations. The consideration of temporal and spatial resolutions and panoramic measurement at different scales are two major challenges. Hence, the prospects for technical advancement in this field are discussed finally.