<title>Interaction of optical beams and space-charge waves (SCW) in photorefractive crystals in the presence of ac electric field</title>

Abstract

Excitation of SCW in photorefractive crystals by two-wave mixing in the presence of both dc and ac electric fields is analyzed. It is shown that an optical grating can be recorded in the crystal in the absence of a detuning between the beams as effectively as in the presence of the optimum detuning. It is also shown that SCW spatial subharmonic instability is possible in this case, and a threshold condition for subharmonic generation is derived.