Space-time processing with photorefractive volume holography

Photorefractive volume holography for processing ultrashort optical pulses carrying spatial, temporal, and spatiotemporal optical information is intro duced. These new holographic methods can process temporal information, i.e. , the temporal evolution of optical pulse signals, in addition to the usual spatial information. Photorefractive volume holographic materials provide the medium necessary for recording and reconstruction of such optical infor mation in real time. Spatial and temporal holography with photorefractive v olume holographic materials are introduced, compared, and discussed. The di rect time-domain holography is shown to possess two disadvantages, the tow fringe contrast and the limited recording rime, which is over come by using the method of spectral domain holography. Applications of direct time-doma in and spectral-domain holography Sol image processing, temporal matched fi ltering, optical pulse shaping, three-dimensional (3-D) optical storage, an d optical interconnects are discussed. Furthermore, the combined space-time holographic processing that allows the conversion between the spatial and the temporal optical information carrying channels is introduced. This meth od is used to demonstrate experimentally parallel-to-serial and serial-to-p arallel data conversion for one-dimensional (1-D) images and image-format d ata transmission. The demonstrated holographic processors provide the advan tages of self-referenced signal transmission and self-compensation for opti cal dispersion induced by the holographic materials, communication channel, as well as other optical components.