Linear detection of phase-modulated optical signals with ac-biased cubic photorefractive crystals : Influence of coupling effects

We apply the theory of vectorial wave coupling in cubic photorefractive crystals subjected to ac-field to describe the transformation of a momentary phase changes of one of the input beams into the output intensity modulation (the so-called grating translation technique). In contrast to the previous studies, we take into account the change of the space-charge field amplitude across the crystal owing to the coupling effects. The theory developed is employed to optimize the conditions for the linear signal detection under polarization filtering for the transverse and longitudinal optical configurations. We also analyze the possibility of the linear detection without polarization filtering.