Dispersion of linear and nonlinear refractive index in chalcogenide glass

Fundamental mechanisms of the intensity-dependent refractivity in optical glasses have been less understood than those in two-level atoms and crystalline semiconductors. In the work, the concept based on the strong dependence of nonlinear refractive index on the bandgap energy is developed. Spectral dependence of the nonlinear refractive index near the bandgap frequency in chalcogenide glasses is considered and compared with direct- and indirect gap crystalline semiconductors.