Laser damage threshold of Ge8As23S69 films irradiated under single- and multiple-pulse femtosecond laser

In this study, the single- and multiple-pulse laser-induced surface damage characteristics of the Ge8As23S69 chalcogenide film under the femtosecond laser irradiation were experimentally investigated. The 1-on-1 and S-on-1 methods were utilized to measure the femtosecond laser damage by using single and multiple pulses, respectively. The femtosecond laser-induced damage threshold (LIDT) was obtained using linear regression method by measuring the damage morphology under different pulse energies and pulse numbers of the femtosecond laser. Results show that the LIDT of the film under single-pulse radiation is higher than that under multiple-pulse radiation because of accumulation and defect effects. For the single-pulse radiation, LIDT is attributed to the field enhancement effect, multiphoton ionization, and avalanche ionization. The single-pulse damage threshold of Ge8As23S69 films is 232.548 mJ/cm2. For the multiple-pulse radiation, the LIDT of the film decreases with increasing pulse number due to accumulation and defect effects.