We investigate the dynamics of Laser-Induced Gratings (LIG) in a medium showing optical bistability due to increasing absorption (e.g. CdS). Fast switching processes occur in selfdiffraction both in the diffracted and transmitted beams.
The switching dynamics of thermally induced optical bistability due to increasing absorption is investigated in thin CdS platelets, at room temperature. Fast and slow components can be observed during the switching process, they depend on the holding point intensity and on the switching pulse energy. It is shown that the transverse relaxation of the temperature in the sample influences this dynamics. The spectral shift of the band to band absorption edge, at the origin of the bistable behavior, is observed in a three beam experiment.
The switching dynamics of photothermal-induced absorption optical bistability is studied in CdS. The bistable element being held near its switching threshold is switched by a pulse of an excimer laser, which can be regarded as δ shaped in time with respect to the thermal relaxation time of the sample. The dynamics of the switching process is influenced by the transverse relaxation of the temperature in the sample. Under appropriate conditions either a slowing down or a fast switching is observed.