Mid-infrared optical nonlinearities of chalcogenide glasses in Ge-Sb-Se ternary system.

Optical nonlinearities of chalcogenide glasses in the Ge-Sb-Se ternary system are investigated at mid-infrared wavelengths (2000 and 2500 nm) with femtosecond Z-scan technique. Strong nonlinear refraction in the chalcogenide glasses is observed at 2000 nm, due to three-photon absorption resonance. In addition, the variation in the nonlinear refraction (γ) of the Ge-Sb-Se glasses shows two jumpoints as mean co-ordination number (MCN) approaches 2.4 or 2.7, consistent with the theoretical predication.