Abstract

Direct laser writing has been applied to the fabrication of complex three-dimensional structures inside optical materials such as SiO₂, SU-8, and Silicon [1,2]. Neodymium-doped yttrium aluminum garnet (Nd:YAG) is one of the most favourable gain media for solid-state lasers owing to its excellent spectroscopic, physical and thermal properties. Although some works have reported experimental DLW for fabrication of waveguides in Nd:YAG [3], there is currently no detailed explanation of the nonlinear optical mechanisms and impact of phenomena such as generation of free carriers induced by multi-photon ionization and plasma formation. In this work, we study for the first time the underlying physics behind nonlinear optical dynamics in ultrafast laser beam propagation during the femtosecond laser processing of Nd:YAG.

© 2019 IEEE