Multiplexed permanent and real time holographic recording in photorefractive BSO

We report permanent hologram recording in crystals of photorefractive bismuth silicon oxide using reversible photochromic effects. At a recording wavelength of 488 nm, exposures of several minutes produce areas of faint discoloration in which the permanent hologram is stored. The normal photorefractive behavior is unaffected, however, permitting spatial multiplexing of both real time and permanent holograms. Experimental results and characteristics of this permanent recording in combination with the photorefractive process are presented.