Mechanism and dynamics of transient and selective laser processing revealed through high-speed observation combined with precision timing control

Abstract

Transient and selective laser (TSL) processing has attracted attention as an ultrafast, high-precision microfabrication method for glass. In TSL processing, the material is locally excited, and the excited region is selectively removed at ultra-high speed. However, its processing mechanism, dynamics, and applicability to other materials remain unclear. In this study, we visualized the processing phenomena using sub-microsecond-scale ultrafast imaging and nanosecond-scale precise timing control. We revealed that the process is triggered by bandgap shrinkage following electron–phonon relaxation. Furthermore, we demonstrated that this method enables the processing of sapphire—a large-bandgap material—at speeds 25,000 times faster than conventional methods.