The recording of a phase volume grating in photorefractive media leads to a stationary energy exchange between the two incident light beams interfering in the crystal—reference and low-intensity probe beam . This energy exchange is caused by a self-diffraction process of the reference beam in the dynamic phase volume grating written in the crystal. The beam coupling is related to the phase shift ψ between the incident fringe pattern and the photoinduced index modulation, and from nonlinear beam-coupling equations it results that the intensity of the probe beam emerging from the crystal takes the form (Fig. 1).
© 1984 Optical Society of AmericaPDF Article