Precision Determination of the Laser-Induced Damage Threshold for Infrared Glasses under Femtosecond Laser Irradiation

In this paper, we report a comparative study of the laser damage properties of three different systems for infrared glasses (As2S3, 70TeO2-15ZnO-5La2O3-10WO3 (TZLW), and 53ZrF4-20BaF2-4LaF3-3AlF3-20NaF (ZBLAN)). The effects of laser pulse power and pulse number on glasses damage crater morphology and damage characteristics were systematically investigated under 800 nm femtosecond laser irradiation. According to the Tauc formula, the bandgap values for As2S3, TZLW, and ZBLAN glasses are 2.01, 2.70, and 4.98 eV respectively. Under femtosecond laser irradiation, a serious edge collapse is found at the edge of the damage crater for the wide-bandgap ZBLAN glass because the high laser energy density affects the accurate calculation of the laser-induced damage threshold (LIDT). According to the characteristics of ZBLAN, glass damage crater size is not sensitive to the pulse numbers. We proposed employing laser direct writing strip damage and using the linear regression method to accurately calculate the damage threshold. The work provides scientific guidance for accurately obtaining the LIDT of optical glass.