Polytopic multiplexing

Abstract

Polytopic multiplexing is a new method of overlapping holograms that, when combined with other multiplexing techniques, can increase the capacity of a volume holographic data storage system by more than a factor of 10. This is because the method makes possible the effective utilization of thick media. An experimental demonstration of this technique is also presented.

Shift-Peristrophic Multiplexing for High Density Holographic Data Storage

“…These methods depend on the effect of Bragg selectivity, which is determined by calculating the thickness of the medium and the wavelength and geometry of the optical system. Multiplexing methods based on other principles include polytopic [19] and aperture multiplexing [20], which are based on conservation of momentum and optical correlation.…”

New optical architecture for holographic data storage system compatible with Blu-ray Disc™ system

“…Up until now, several optical architectures for HDSS have been presented. [5][6][7][8][9][10] These are classified broadly into three categories as shown in Fig. 1.…”

“…The optical architecture for angularly multiplexed recording generally has two optical paths for a signal beam and a reference beam with an off-axis optical configuration. 5,6 Regarding the optical architecture for shift multiplexed recording, a reference beam and a signal beam are bundled on the same optical axis and irradiated on a holographic medium through a single objective lens. 7,8 Regarding the optical architecture for micro hologram recording, two counter-propagating signal and reference beams are configured to record bitwise information similar to the BD system.…”

“…In contrast, it is generally inclined with respect to a holographic medium in angularly multiplexed recording to keep a space for reference beam optics. 5,6 The larger NA of the objective lens is introduced for high density recording, the wider diameter of the objective lens is necessary for enough working distance and coping with *Address all correspondence to: Ken-ichi Shimada, E-mail: kenichi.shimada .ty@hitachi.com fast data transfer rate. 11 Thus, an objective lens with NA 0.85 for compatibility was believed to occupy a space in the HDSS with angularly multiplexed recording and was not to be placed parallel to a holographic medium.…”

Homodyne detection readout for bit-oriented holographic memories

“…Whereas conventional approaches have the advantage of massive parallelism by storing holograms as binary data pages coded by spatial light modulators of typically 10 6 pixels, [1][2][3][4] bit-oriented holographic memories also present attractive features, such as a lightweight write-read head and better compatibility with the conventional surface storage of CDs and DVDs. With such volumetric memories, holograms are spatially and (or) wavelength-multiplexed Bragg gratings inscribed at the waists of two interfering beams.…”