Modeling of picosecond laser-induced plasma amplification inside a microhole and an implied novel technology to drill microholes with varying diameters with depth

Microholes with varying diameters at different depths are very desirable in various important applications. However, it is very challenging to produce microholes with varying diameters when the variation is in a complicated way and/or when the hole diameter is very small. This paper presents physics-based modeling work on the interactions among a picosecond (ps) laser pulse, a pre-existing plasma plume inside a microhole, and the hole sidewall. The modeling work implies the potential feasibility of a novel dual-pulse laser ablation and plasma amplification (LAPA) process for drilling microholes with varying diameters at different depths.