Space-charge gratings in photorefractive crystals controlled by an external variable electric field

Specific features of space-charge gratings excited in photorefractive crystals in the presence of an external variable electric field that exhibits power-law time dependence are studied. It is demonstrated that the process under study substantially depends on a parameter of an increase in the external electric field over a time interval that corresponds to the generation of space-charge gratings in the absence of the field. At a relatively small parameter, the charge can be increased in accordance with variations in the field, charge oscillations with increasing amplitude can be induced, and identical excitation of the gratings can be maintained. At a relatively large parameter, the charge of the gratings is proportional to the time of external action, so that the charge can be controlled using external variable electric field.