Effect of chemical composition on the structure, optical properties and femtosecond laser ablation performance of Ge-Sb-Se glasses

Abstract

The effects of chemical composition on the physical and optical properties and femtosecond laser ablation performance of Ge–Sb–Se glasses with compositions of Ge18SbxSe82-x [x = 5, 10, 15, 17.5, 20, 21.5, 23, 25 (series A)] and GexSb25Se75-x [x = 10, 12.5, 15, 18, 20 (series B)] were systematically studied. With the increase in Sb and Ge in the series A and B glasses, respectively, the glass transition temperature increased at first and then decreased with increasing mean coordination number. The density and refractive index of the sample were mainly affected by Sb content. The third-order nonlinearity was measured at 3.5 μm by Z-scan technique. Raman spectra analysis showed that the proportion of Se–Se bonds declined and that of Sb–Sb and Ge–Ge bonds increased with the increase in Sb or Ge content. The enhancement of nonlinearity was associated with the presence of Sb–Sb homopolar bonds. Series A and B samples were irradiated by femtosecond laser (150 fs, 1 kHz) at 3 μm with different laser powers. The damaged area increased and ablation threshold fluence (Fth) was reduced gradually with the increase in Sb or Ge concentration. Thus, the addition of Sb or Ge can reduce the resistance of Ge–Sb–Se glasses from laser damage.