The effect of the relative position of the bandgap with respect to laser wavelength on the behaviour of DFWM in semiconductor-doped glasses

Degenerated four-wave mixing (DFWM) was realised in five commercial semiconductor-doped glasses (Corning CS3–66, CS3–67, CS3–68, CS3–69, CS3–70). The reflectivity obtained for each glass seems very dependent on the energy excess (E=hv–E _g) and relatively independant on l, the product of the absorption coefficient () by the sample thickness (l). The decay time of the DFWM signal was measured for each glass. The relaxation was found to be different when the photon energy is under or over the gap.