Nonlinear optical and quanta-dimensional effects in monoselenide of gallium and indium

Nonlinear light absorption and its time evolution at high optical excitation levels in GaSe and InSe layered crystals have been experimentally investigated. It is shown that the nonlinear absorption observed in InSe in the region of exciton resonance is due to the exciton-exciton interaction. The effect of filling the zones detected in GaSe at high excitation intensities leads to a change in the absorption coefficient and the refractive index. For InSe nanoparticles obtained by the chemical deposition method, a quanta-dimensional effect was observed; the width of the forbidden band was dependent upon the dimensions of the nanoparticles.