scispace - formally typeset
Search or ask a question
Author

Z H Song

Bio: Z H Song is an academic researcher. The author has contributed to research in topics: Holography & Multiplexing. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: A novel multiplexing scheme for dense holographic storage in photorefractive crystals, spatioangularmultiplexing, is described in detail and succeeded in storing 756 high-resolution patterns in an Fe:LiNbO(3) crystal of volume 1 cm(3), with an average diffraction efficiency of 0.5%.
Abstract: A novel multiplexing scheme for dense holographic storage in photorefractive crystals, spatioangular multiplexing, is described in detail. Compared with spatial multiplexing, spatioangular multiplexing increases the storage capacity by fully utilizing the volume of the storage medium. On the other hand, spatioangular multiplexing reduces the number of holograms overlapping any one hologram in a given volume and so increases the diffraction efficiency achievable as compared with angular multiplexing. Using this scheme, we succeeded in storing 756 high-resolution patterns in an Fe:LiNbO(3) crystal of volume 1 cm(3), with an average diffraction efficiency of 0.5%. This large database is designed for practical use in a novel associative-memory system, called a high-order feedback neural network.

13 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this article, a real-time shift-invariant VanderLugt correlator (VLC) was implemented with a ∼37 μm thick bis-triarylamine side-chain polymer matrix photorefractive(PR) composite operating at ∼1.532 nm wavelength.
Abstract: We demonstrated a real-time shift-invariant VanderLugt correlator (VLC). The VLC was implemented with a 37 μm thick bis-triarylamine side-chain polymer matrix photorefractive (PR) polymer composite operating at 532 nm wavelength. Correlation selectivity was enhanced by real-time edge enhancement. The advantage of the VLC is that its architecture allows overcoming the PR material response speed. A correlator of this type enables a fast shift-invariant search of a large optical image database. A high degree of shift invariance in our correlator was possible because of the material thickness. The angular bandwidth of this material was measured experimentally in a degenerate four-wave mixing setup, and it was found to be in a very good agreement with the theory.

15 citations

Journal ArticleDOI
TL;DR: A parametric extension of the classically derived backward-recursion algorithm that compensates for the intermingling effects of recording geometry, writing-beam intensity variations, and unique crystal behavior is presented.
Abstract: The gradual reorientations in crystal geometry encountered during angle-multiplexed holographic recording with obliquely incident recording beams can create significant parametric exposure-time and recording-angle dependencies in both grating writing- and erasure-time constants. We present a parametric extension of the classically derived backward-recursion algorithm that compensates for the intermingling effects of recording geometry, writing-beam intensity variations, and unique crystal behavior. We present experimental data for a sequence of 301 holograms recorded with the goal of equal hologram strength and, separately, the same sequence recorded with the goal of equal hologram reconstruction intensity-which are different cases for a steeply incident readout beam.

11 citations

Journal ArticleDOI
TL;DR: The photorefractive properties of 0.62PbTiO3 single crystals have been investigated by the two-wave mixing experiment as discussed by the authors, and the maximal gain coefficient is 5.4cm−1, the effective trap density is 1.2×1016cm−3, and the normalized photore-fractive response time under 1W∕cm2 illumination is 0.5s at a wavelength of 632.8nm.
Abstract: The photorefractive properties of 0.62Pb(Mg1∕3Nb2∕3)O3–0.38PbTiO3 single crystals have been investigated by the two-wave mixing experiment. The maximal gain coefficient is 5.4cm−1, the effective trap density is 1.2×1016cm−3, and the normalized photorefractive response time under 1W∕cm2 illumination is 1.5s at a wavelength of 632.8nm. The dominant charge carrier was identified as holes from the direction of two-wave mixing energy transfer.

11 citations

Journal ArticleDOI
TL;DR: In this paper, a three-dimensional disk-type holographic storage using spatioangular multiplexing with a spherical reference beam is analyzed and experimentally demonstrated, and the overlapping factors between adjacent holograms in a track and between adjacent tracks in a disk are determined based on the selective angles calculated by coupled-wave theory.
Abstract: Three-dimensional disk-type holographic storage using spatioangular multiplexing with a spherical reference beam is analyzed and experimentally demonstrated. The overlapping factors between adjacent holograms in a track and between adjacent tracks in a disk are determined based on the selective angles calculated by coupled-wave theory. There are 10000 holograms stored along 5 tracks in a sector of a single iron-doped lithium niobate crystal.

11 citations

Proceedings ArticleDOI
21 May 2006
TL;DR: Results are shown from a real-time shift-invariant VandeLugt correlator in a new photorefractive polymer material that allowed for fast shift-Invariant search of a volume holographic database.
Abstract: We show results from a real-time shift-invariant VandeLugt correlator in a new photorefractive polymer material. The thickness of the material allowed for fast shift-invariant search of a volume holographic database.

11 citations