Diffraction properties of photorefractive gratings with polarization asymmetry between the write-read beams

Abstract

A dynamic hologram can always be updated to allow for any movement of the optical components (e.g., alignment drift over time). This makes the dynamic hologram useful in optical signal processing. We have studied the diffraction efficiency η of dynamic photorefractive gratings as a function of the polarization asymmetry between simultaneous write-read beams of comparable intensity. Photorefractive two-beam coupling effects are present both between the writing-beam pair and between the read beam and its diffracted beam. The nonlinear and nonreciprocal nature of diffraction efficiency1,2 as a function of read-beam intensity is examined for various ratios of ΓW/ΓR, where ΓW (ΓR) is the two-beam coupling constant during writing (reading). The diffraction efficienty η is also expected to show oscillatory behavior as a function of beam ratio during writing,3 when the write beams are ordinary-polarized and the read beam is extraordinary-polarized.