Laser-Matter Interaction in Dielectrics: Insight from Picosecond-Pulsed Second-Harmonic Generation in Periodically Poled LiTaO3

Frequency conversion of lasers is used in many applications, but as beam intensity continues to increase, one must reconsider exactly what occurs within the target material. Based on data for short-pulse second-harmonic generation by a periodically poled nonlinear optical crystal, the authors develop a two-temperature model of laser-matter interaction in a dielectric. This extended description of frequency conversion and beam propagation in the crystal accounts for the effects of photoinduced plasma generation, thermal and plasma-induced dephasing, and related phenomena of optical breakdown and filamentation.