Effect of self-diffraction on erasure dynamics during readout at different wavelengths and geometries in photorefractive materials

Certain memory applications based on photorefractive media require the ability to conveniently fix holograms. An attractive alternative is to sufficiently prolong the readout time. Low photoexcitation at long wavelength augmented by self-diffraction can increase readout time by a few orders of magnitude. The interaction of the writing and readout waves, both of the same wavelength, with the photorefractive space charge field has been investigated theoretically and experimentally. Dynamics of beam coupling and self diffraction, in certain geometries, can lead to an initial increase followed by non-exponential decay of the diffracted signal during readout. Here we study how the difference in gain, lifetime, photoexcitation and absorption at different wavelengths - which require changing incident angles to satisfy the Bragg condition - affect the decay dynamics of photorefractive gratings