Holographic random access memory (HRAM)

Abstract

We examine the present state of holographic random access memory (HRAM)

Holographic data storage systems

“…Such a scheme has been suggested by several authors [47], [48] and implemented in simple proof-of-concept demonstrations for materials displaying strong scattering [49]- [51]. More recently, digital HDSSs using phase-conjugated readout have been evaluated at Caltech [9], [52] and IBM [1].…”

“…At a transfer rate of 5 MB/s-typical for current magnetooptic drives-data density for HDSS is 50-70 times higher using a laser with two orders of magnitude more power. By varying the materials and systems parameters according to (52), the curve of Fig. 50 can be modified.…”

Coherent Optical Information Systems

“…Each page can be thought of as an additional layer in a holographic memory disk, leading to storage densities roughly two orders of magnitude better than are possible with DVDs (28). Because the recorded pages of data are holograms, it is possible to read them out using phase conjugation (29), in which case the hologram is illuminated with a beam that is the same as the reference used during recording except that it propagates backward. This results in the reconstruction of the signal beam that is also propagating backward, and in doing so it comes to focus back at the plane of the SLM.…”

System measure for persistence in holographic recording and application to singly-doped and doubly-doped lithium niobate

“…We also assume that in such a system, we need to have N ph photons for each pixel with area Ꮽ pixel at the detector to obtain an acceptable signal-to-noise ratio. 15 We define the measure for persistence, R͞ն, as the number of times we can read the information in the entire module ͑all M holograms͒ before the diffraction efficiency of each hologram falls below the minimum acceptable value ͑ min ͒.…”