Compositional dependence of the nonlinear refractive index of new germanium-based chalcogenide glasses

In this paper, we report results of n2 measurements of new chalcogenide glasses in the Ge–Sb–S–Se system using a modified Z-Scan technique. Measurements were made with picosecond pulses emitted by a 10 Hz Q-switched mode-locked Nd-YAG laser at 1064 nm under conditions suitable to characterize ultrafast nonlinearities. The nonlinear index increases up to 500 times the n2 of fused silica with an increase in the Ge/Se ratio and a decrease with an increase of the Ge/Sb ratio. We confirmed, using Raman spectroscopy, that the nonlinear refractive index depends on the number of Ge–S(Se) and Sb–S(Se) bonds in the glass network. Sulfide glasses were shown to have a nonlinear FOM near or <1, at 1064 nm.