LINEAR AND NONLINEAR-OPTICAL PROPERTIES OF CHALCOGENIDE GLASSES

The compositional dependence of the nonlinear refractive index, n(2), for As-S, Ge-Se, As-Se and Ag-As-S systems is investigated. The dispersion of the linear refractive index, n, and the linear absorption coefficient, alpha, are calculated for As30S70, AS(33)S(67), As40S60, Ge18Se82, Ge22Se78 Ge33Se67, As40Se60 and Ag-As40S60 (containing similar to 20 at.% of Ag) compositions. The Boling's formula is used to predict n(2) from the dispersion and the magnitude of n. Compositional trends of n, n(2) and E(g) show non-resonant nonlinearity in the As-S and Ge-Se system, while the large n(2) value observed for the As40Se60 composition can be attributed to an increasing contribution of absorptive type nonlinearity in the given wavelength region. Deviations from the stoichiometric compositions in the As-S and Ge-Se systems result in larger n(2).