Shift Selectivity and Hologram Playback Margin Dependence on the Average Speckle Size of a Randomly Phase Encoded Reference Beam

Abstract

Several important hologram reconstruction parameters of shift multiplexing with a randomly phase encoded reference beam were investigated as functions of the reference beam average speckle size at the medium. Those are shift selectivity, reference beam defocus margin, and medium tilt margin. It was confirmed that these parameters are linearly dependent on the average speckle size in certain directions. The exception was the in-track direction medium tilt margin which is dominated by the Bragg matching condition. We found that smaller average speckle size is preferable in view of achieving higher recording density, while larger average speckle size is desirable in view of having wider playback margins. Based on the experimental results, the multiplexing of 300 holograms per unit area was demonstrated with a polymer medium with sufficiently low bit error rates.

Simulation of Holographic Data Storage for the Optical Collinear System

“…It has been reported that the average speckle size is much longer in the longitudinal direction than in the transversal direction, 8) which corresponds also well to our simulation results.…”

“…In order to validate our simulation of the media shift, we compared the simulation result with the speckle theory. It has been reported that in hologram recording, the medium shift selectivity and the hologram playback margin are comparable to the average speckle size, 7,8) Áx as defined:…”

Enhancement of Repositioning Tolerance by Directionally Controlled Shift Selectivity of Speckle-Multiplexed Holograms

“…Accordingly, the shift selectivity along this direction is also alleviated. 1,10) By combining the spatial multiplexing of the regions of the speckle-multiplexed holograms along this direction, storage capacity will be further increased with sufficient repositioning tolerance.…”

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.…”