Abstract

The use of photoinduced dynamic refractive-index gratings for incoherent-to-coherent optical conversion or spatial light modulation has been reported, such as, four-wave mixing phase-conjugation in BSO crystals [1,2] and anisotropic self-diffraction in KNbO₃ crystals [3]. The coherent reconstruction in these experiments was a negative replica of the incoherent input image. We have found a new phenomenon in SBN:Ce that the coupling direction can be altered and coupling gain can be changed by an external electric field [4]. In accordance with this effect, in the present paper a new method for incoherent-to-coherent conversion and spatial light modulation using two-beam coupling in SBN:Ce is proposed, which is suited to control the replica contrast to be either negative or positive.

© 1989 Optical Society of America