Photoexpansion and nano-lenslet formation in amorphous As2S3 thin films by 800 nm femtosecond laser irradiation

Abstract

Two step laser processing has been used for the formation of nano-lenslets transmitting in red/infrared region of the optical spectrum on the surface of arsenic sulphide glass films. In the first step the films were obtained by pulsed laser deposition (248 nm), while in the second step the lenslets were created by low power femtosecond (800 nm) laser irradiation. Photoexpansion of the material along with simultaneous migration of chalcogen atoms in the irradiated area was the main phenomena involved in the generation of these structures. The maximum photoexpansion observed was 5.1%. At higher laser power, material ablation was evidenced.