|About this Abstract
||MS&T23: Materials Science & Technology
||Solid-state Optical Materials and Luminescence Properties
||Surface Morphology and Fracturing of Femtosecond Laser-irradiated Calcium Fluoride
||Emma DeAngelis, Justin Twardowski, Conrad Kuz, Enam Chowdhury
|On-Site Speaker (Planned)
CaF2 is a high bandgap material which transmits light ranging from mid-IR to far-UV, making it a very useful optical material for high power laser applications. When exposed to ultrashort laser pulses significantly higher than the damage threshold, CaF2 exhibits surface fractures that lie along the (100) cleavage planes and appear as raised bands above a laser-ablated crater. In this work, CaF2 with a polished (100) surface was irradiated with 1030 nm, 77 fs pulses, resulting in rectangular cracks. Similar femtosecond laser damage features have been found in cubic crystals such as NaCl and MgO, as well as monoclinic β-Ga2O3. This unique damage morphology may be due to anisotropic thermal conductivity, which causes thermal stress to overcome mechanical strength more easily in crystallographic directions with low conductivity. Laser-induced defects may also play a role by deforming the lattice and fracturing, rather than thermally relaxing.