Temporal bit-sequence signal storage by using angular-multiple spectral volume holography (SPLUME)

A novel method is proposed for storing temporal bit sequences based upon the angular-multiple holographic recording of optical spectral components. The key technology is the spatially resolved generation of multifrequency reference beams whose phases are synchronized to the sideband of the optical cell. A preliminary experiment is made using an acoustooptic modulator for generating the multifrequency reference beams. In the experiment, a 4-bit-long nonreturn-to-zero 200-Mbit/s sequence is successfully recorded and regenerated from a photorefractive BaTiO₃ crystal as a real-time holographic medium. The recording bit rate is limited by the bandwidth of the modulator of the reference beam, not by the temporal response of the holographic medium. Cascading modulators is useful to broaden the bandwidth of the generated reference beam, resulting in expansion of the recording bit rate. Recording of an 8-bit-long 400-Mbit/s sequence is successfully demonstrated by cascading two modulators