OPTICAL HYSTERESIS AND LIGHT ABSORPTION IN a-As_2S_3 AND c-As_2S_3

摘要

Results of the experimental investigations of nonlinear absorption of laser pulses in amorphous a-As_2S_3 films are presented. The optical transmission hysteresis and reversible film photodarkening at interbank excitation of a-As_2S_3 films in a blue-green spectral region is reported for the first time. It was suggested that the nonlinear light absorption could be explained by taking into account the light interaction with nonequilibrium localized lattice vibrations anharmonically coupled with the extended phonons. The measurements of peculiarities of the pulse absorption in crystalline c-As_2S_3 films can confirm the proposed explanation.