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Picosecond mid-IR laser induced surface damage on Gallium Phosphate (GaP) and Calcium Fluoride(CaF2)


Picosecond mid-IR USPL induced surface damage on a Gallium Phosphate (GaP) and Calcium Fluoride (CaF2) is reported. A semiconductor GaP and a dielectric material CaF2, that are transparent over3–10μm, were exposed to one picosecond mid-IR light (4.7μm) to investigate laser-induced surface morphological changes on the target The initiation of damage along the polishing scratch line of GaP and the random location of damage digs on the CaF2 suggests that the mid-IR picosecond laser-induced damage on targets started from intrinsic surface defects. Multiple pulse irradiations produced periodic corrugated surface structures (ripples) perpendicular to the polarization of light on both GaP and CaF2. In terms of the orientation and the spacing between ripples, observed ripples have common features with previously reported ripples.