Multilayer volume holographic optical memory

Abstract

We demonstrate a scheme for volume holographic storage based on the features of shift selectivity of a speckle reference-wave hologram. The proposed recording method permits more-efficient use of the recording medium and yields greater storage density than spherical or plane-wave reference beams. Experimental results of multiple hologram storage and replay in a photorefractive crystal of iron-doped lithium niobate are presented. The mechanisms of lateral and longitudinal shift selectivity are described theoretically and shown to agree with experimental measurements.

Spatial arrangement of speckle-multiplexed holograms using directional control of shift selectivity with holographic diffuser

“…This method enables us to relax the shift selectivity in a shift direction of holographic medium. We also notice that the hologram which is recorded with the speckled reference beam intrinsically has the relaxed shift selectivity along the propagation direction of the reference beam [1,5]. The hologram can be easily multiplexed and read out spatially along the "controlled" and the "intrinsically relaxed" directions by utilization of these relaxed shift selectivities.…”

“…The hologram recorded with speckled reference beam has the acute shift selectivity. The nature is suitable for increasing multiplicity [1][2][3][4].…”

Crosstalk analysis of multilayer collinear volume holographic data storage

“…To achieve the theoretical storage density of 1/λ 3 , various storage configurations and multiplexing techniques have been proposed [5][6][7]. In order to make efficient use of the dynamic range in the recording medium, multilayer storage was proposed by using off-axis holographic method [8][9][10]. Later, the techniques of coaxial holographic and multilayer storage were combined, which enabled the areal data density to increase by a factor of four compared with traditional one-layer shift-multiplexing collinear system [11].…”

Selectivity and tolerance calculations with half-cone-shaped reference beam in volume holographic storage

“…Because of the simple technical realization of the method, shift multiplexing is one of the most promising alternatives for exploiting the data density potential of volume holographic storage [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The primary advantage of the methods is the simple realization of multiplexing using the track and focus servo system or disc rotation [7,11].…”

“…There are no auxiliary optical or mechanical elements needed to shift the overlapping holograms relative to each other. For holographic systems that use shift multiplexing, one applies different forms of reference beams: full or half cone beams with spherical wave front [1, 2, 6-9, 15, 16], an array of aperture limited plane waves with different directions [5, 10-12,], or diffuse reference beams [3,4]. The last two methods are called correlation shift multiplexing, or spatial multiplexing [4].…”