Raman gain and femtosecond laser induced damage of Ge-As-S chalcogenide glasses

Abstract

Chemical stoichiometric Ge-As-S glasses were prepared, and their thermal properties, refractive index (n), optical bandgap, Raman gain, and femtosecond laser damage were examined. Results revealed that the n and density (ρ) of the glasses decreased as Ge concentration increased, whereas the bandgap and glass transition temperature (Tg) increased. The Raman gain coefficients (g_R) of the samples were calculated on the basis of spontaneous Raman scattering spectra. g_R decreased from 2.79 × 10^-11 m/W for As₂S₃ to 1.06 × 10^-11 m/W for GeS₂ as Ge concentration increased. However, the smallest g_R was 100 times higher than that of fused silica (0.89 × 10^-13 m/W). When these glasses were irradiated by a laser with a pulse width of 150 fs and a power of 33 mW at 3 μm, the damaged area and depth decreased and the damage threshold increased gradually as Ge concentration increased. Raman spectra and composition analysis indicated that surface oxidation probably occurred and sulfur gasified at a high laser power. Although the g_R decreased as Ge was added, the laser damage threshold of Ge-As-S glasses was higher than that of the As₂S₃ glass. Thus, these glasses are potential materials for Raman gain media.

Mid-infrared femtosecond laser-induced damages in As2S3 and As2Se3 chalcogenide glasses

“…Zhang et al . reported that the damage threshold increased with increasing Ge concentration in Ge-As-S glasses irradiated by femtosecond laser pulses at an average power of 33 mW 7 . However, a rigorous investigation on the laser damage threshold of ChGs in the femtosecond regime is still absent.…”

Advances in femtosecond laser processing of optical material for device applications

“…108 Additionally, Ge-As-Se glasses were observed to have a higher laser damage threshold compared to that of As 2 S 3 glasses. 110 This is encouraging for the future fs laser writing of devices in Ge-As-Se-based chalcogenide.…”

“…With increasing Ge content into the composition, the glass‐transition temperature was shown to increase while the thermal expansion coefficient decreased . Additionally, Ge‐As‐Se glasses were observed to have a higher laser damage threshold compared to that of As 2 S 3 glasses . This is encouraging for the future fs laser writing of devices in Ge‐As‐Se‐based chalcogenide.…”

Ultra‐large mode area mid‐infrared fiber based on chalcogenide glasses extrusion

“…For fluoride fibers, although the fibers possess low loss in mid‐infrared laser delivery, they are easily prone to deliquescence and too environmental sensitive to endure high‐power transmission. In comparison, chalcogenide (ChG) glasses exhibit excellent properties including a wide transparency range from the mid‐infrared (MIR) to far‐infrared, superior thermal and chemical resistance, and high refractive indices and nonlinearity, 14,15 but their laser damage threshold is low 16,17 . Fortunately, ChG glasses are fabricated to LAM fiber, which can effectively broaden the spectral range and improve the laser power threshold.…”