Compensation Method for Phase Fluctuation in Holographic Data Storage

Abstract

A method that records accurate information of an object beam is discussed. Before conducting our experiment, the effect of phase fluctuation was calculated using the coupled wave theory. Simulation results showed that the fringe amplitude decreased as the phase noise level increased. We propose a method for phase compensation even if a modulated object beam, which consists of black-and-white pixels, is used with a millisecond recording time. A recording experiment was conducted, in which even pages were without compensation and odd pages were with compensation with 100 angle multiplexing. The obtained results indicate that the mean brightness was increased by 2 ×105, and the mean error count for each page was reduced from 17 to 13 by improving the diffraction efficiency.

Method of Phase and Amplitude Modulation/Demodulation Using Datapages with Embedded Phase-Shift for Holographic Data Storage

“…There have been many techniques for achieving the potentially enormous capacity of holographic data storage systems from the viewpoints of the optical system, hologram multiplexing, and coding technique among others. [1][2][3][4][5][6][7][8][9][10][11][12] Recently, other approaches have been studied to increase the storage capacity and density of these systems by spatial quadrature amplitude modulation (SQAM), which utilizes the phases of the object beam carrying the datapage pixels as the stored data in addition to the intensities. [13][14][15][16] On the other hand, since the phase of light waves cannot be directly detected by a CCD camera, an interferometric technique should be used in the detection system for the SQAM-based holographic data storage system.…”