Self-diffraction of light and wavefront reversal in four-wave interaction in cadmium sulfide single crystals

An experimental investigation was made of the specific characteristics of wavefront reversal (WFR) and selfdiffraction of light from dynamic gratings induced near the fundamental absorption edge of cadmium sulfide. As a result of the thermal shift of the band gap $E_g$=2.42 eV relative to the laser photon energy $\hbar\omega$ =2.331 eV, it was possible to achieve resonant modulation of the refractive index and to optimize the conditions for maximizing the WFR and self-diffraction efficiencies. An investigation was made of the dependence of the reflection coefficient of the reversed wave on the degree of excitation and on the thickness and temperature of the samples. It was found that efficient WFR in terms of energy can be achieved at the fundamental absorption edge of direct-gap semiconductors.