Recording procedures for high-quality signal readout in self-referential holographic data storage

Abstract

Two methods are proposed to improve the readout quality of signals in self-referential holographic data storage (SR-HDS), in which no reference beam is required to record and read digital data holographically: the off-the-focus (OtF) method and the oversampling additional pattern (OsAP) method. The focal point is located outside of the recording medium in the OtF method, and the signal pattern is recorded with an additional pattern that possesses a higher spatial frequency than the signal pattern in the OsAP method. Experimental results show that both methods are effective for drastically improving the signal-to-noise ratio (SNR). In addition, through numerical simulation, it can be observed that the readout quality is improved by the achievement of homogeneous hologram distribution.

Numerical simulations on inter-page crosstalk characteristics in three-dimensional shift multiplexed self-referential holographic data storage

“…In this case, although the readout quality is significantly degraded, the degradation can be avoided by using an additional pattern with finer pixels than the signal pattern. 28)…”

“…high-quality readout as described in the previous section. 28) In addition, binary patterns with a phase difference of π=2 and π are used as the signal and additional patterns, respectively. Also, we assume that the refractive index changes of the recording medium exponentially saturate with the exposure energy, which is given by Ánðx; y; zÞ ¼ n max 1 À exp À Iðx; y; zÞ…”

“…A self-referential holographic data storage (SR-HDS) can realize a purely one-beam HDS system by recording and reading differently from the other two optical systems. [26][27][28] Because the SR-HDS is a reference-less system, the compact HDS system as well as the collinear optical system can be realized. In addition, in SR-HDS, because the entire region of the writing beam can be used as the signal region, the recordable data bits at a given time are higher than the collinear optical system.…”

Linear phase encoding for holographic data storage with a single phase-only spatial light modulator

“…Self-referential holographic data storage can realize a recording system using a single phase-only SLM without additional optical elements [19,20]. In addition, this system does not require a reference beam to record a data page, and thus an optical setup is simple and compact compared with the conventional holographic storage systems.…”