Numerical estimation of storage capacity in reflection-type holographic disk memory with three-dimensional speckle-shift multiplexing

Abstract

Maximum storage capacity in a reflection-type holographic memory with three-dimensional speckle shift multiplexing is investigated numerically. An explicit expression of storage capacity is derived on the basis of interpage crosstalk noise. We fabricate a simulator to evaluate reflection-type holographic data storage by calculating wave propagation, recording a hologram, and reconstruction by scalar diffraction. We calculate the properties of the resultant diffraction efficiency, that is the noise, at the first null in the speckle-shift multiplexing. Numerical results indicate that the storage capacity is proportional to the numerical aperture to the fourth power and to the volume of the recording medium and is inversely proportional to the wavelength to the third power. Achievable storage capacity is discussed.

Design of Reference Pattern and Input Phase Mask for Coaxial Holographic Memory

“…Recently, a holographic memory has been expected as a nextgeneration optical memory with a large capacity and a high data-transfer rate. Various techniques [1][2][3][4][5][6][7] related to a holographic memory such as a two-axis method and a coaxial method have been studied. In a conventional coaxial method, a random binary phase mask 8) is used to reduce the useless consumption of the dynamic range of a recording medium caused by the high intensity DC peak of an illuminating beam.…”

Improvement of Storage Capacity Using Confocal Scheme in Reflection-Type Holographic Memory System with Speckle Shift Multiplexing

“…There are numerous studies in which the storage capacity in holographic memory [1][2][3][4][5] was assessed or increased. Recently, the storage capacity in a magnetic hard disk drive (HDD) has exceeded 3 Tbyte.…”

“…We have been investigating a reflection-type holographic memory system with speckle shift multiplexing. [5][6][7][8] A reflection-type hologram has a feature of a short interaction owing to the short period of the grating. This feature enables us to use three-dimensional shift multiplexing.…”

“…11,12) The storage capacity of the reflection-type holographic memory system with speckle shift multiplexing is derived numerically using a holographic memory simulator on the basis of scalar diffraction theory. 5,13) The maximum storage capacity is estimated to be 2.7 Tbyte/disk in a recording medium with a thickness of 0.5 mm and a 5-in.-diameter disk when the wavelength of the laser light is 405 nm. Storage capacity is derived by taking the interpage cross-talk noise into account.…”

“…9 and 10 in ref. 5, interpage crosstalk noise by three-dimensional shift multiplexing without the confocal scheme is individu-ally added because there is no cross-correlation between the recoded patterns. From these facts, it is expected that the aperture can eliminate the interpage crosstalk noise both along the depth direction and in-plane.…”