Femtosecond Laser Direct Writing of Antireflection Microstructures on the Front and Back Sides of a GaSe Crystal

The development of antireflection coatings is crucially important to improve the performance various photonic devices, for example, increase efficiency harmonic generators based on high-refractive index crystals with significant Fresnel losses. A promising technique reducing radiation reflection change refractive by fabrication microstructures (ARM) surface. This paper presents results ARM direct writing surfaces a nonlinear GaSe crystal (of ε modification, according Raman and photoluminescence spectroscopy data) using fs laser multiples approach. An in transmission from 65% 80% an fabricated one side up 94% ARMs both sides demonstrated. increasing pulse energy, as well number pulses used formation single crater, shown. experimental are qualitative agreement simulation measured profiles morphology structures.