Beam Splitter Model of Two-Beam Coupling in Photorefractive Materials
Jan M. Yarrison-Rice, Perry R. Rice, and D. Jeffrey Rowan** - Journal of Modern Optics 42, 1971 (1995)
The phenomenon of two-beam coupling in photorefractive crystals results from the interaction of two beams with the index grating written by those two beams. In this paper we show that the process can be understood by considering the photorefractive crystal to be a nonlinear beam-splitter, with reflectivity and transmission coefficients dependent upon the relative intensity of the two beams. The relative phase relationships upon reflection, determined by the Fresnel equations, as well as the phase shift between the intensity and index grating, are the sources of the asymmetric coupling. A simple derivation of coupled mode equations describing two-beam coupling based upon the beam splitter model is proffered.
** Graduate student at M. U.