Photorefractive memories for optical processing

Abstract

The field of three-dimensional optical storage has lately witnessed a tremendous increase of interest from both the scientific and the industrial communities. Volume holographic storage was proposed by van Heerden [1] shortly after the introduction of the laser, and interest in this technology has continued at varying degrees of intensity since. Holography potentially combines the advantages of high storage densities and ease of parallel data readout. The storage of multiple pages of information in the same volume and the parallel readout of many bits promise fast data access times and a high data bandwidth. Furthermore, in holography the information is distributed throughout the storage medium and is therefore less sensitive to local material imperfections. If Fourier holograms are stored in holographic memories, effects of imperfections in the medium are distributed throughout the page, and are not linked to individual pixels; thus valuable bits of data are not lost, and only the signal-to-noise ratio is diminished. This is in contrast to magnetic and conventional optical recording, where an individual bit of information is represented by a highly localized change in some physical property. This advantage may be less important in holographic digital data storage when additional redundancy of information storage and error correction can be easily implemented. © 2007 Springer.