Stratified volume holographic optical elements

Abstract

A computational algorithm for analyzing diffraction properties of optical devices, the optical beam propagation method, has suggested a new class of devices by which Bragg regime (thick grating) response can be obtained from a spaced sequence of thin grating layers. Such stratified volume holographic optical elements (SVHOE's) can emulate distributed volume gratings in terms of diffraction efficiency and angular selectivity and in addition possess periodic diffraction properties that might serve, for example, as interconnections for optical cellular logic arrays. SVHOE's also offer a unique capability for altering the device diffraction response on a layer-by-layer basis, allowing for control of both the diffraction peak width and the angular separation of adjacent peaks.

Anisotropic diffraction of stratified volume holographic grating in photorefractive media

“…3(a) shown, the diffraction properties of SVHOE shows period Bragg selectivity properties with a period of NÀ1 two grating diffraction peaks, in which NÀ2 of the two-grating peaks have been suppressed by the interior gratings, and which agree perfectly well with the numerical results of Ref. [1]. When the buffer-layer thickness and grating-layer thickness are hold constant, as the number of layers of SVHOE increase, the most peak of diffraction increase, but the central width of the most diffraction peaks decrease.…”

“…They have many important applications in optical information processing and computing. Many novel devices can be made, such as optical array generation [1][2][3][4], wavelength notch filtering, grating spatial frequency filtering [3,4], and beam-scanning elements [5].…”

“…The concept of SVHOEs was first introduced by Tanguay and Johnson [1,2]. A SVHOE consists of multiple layers of thin photosensitive holographic recording layer interleaved with optically passive buffer layers.…”

“…Since not all thin-film photosensitive materials can be thin enough to yield strictly Raman-Nath diffraction behavior within each modulation layer under all possible conditions, Yakimovich [6] studied the diffraction behavior of multiply grating which modulation layers individually exhibit Bragg diffraction behavior. In addition, different materials have been used in the fabrication of SVHOEs, such as photopolymers [3], dichromated gelatin films [7], and photoresist [1,8]. Comparing with these materials used in the fabrication of SVHOEs, photorefractive crystals are the most promising holographic data storage materials for their large storage density and reversibility.…”

<title>Real-time splitting behavior of stratified holographic optical elements</title>

“…The corresponding angular properties of the diffraction of this kind of grating and the physical origin of these properties are discussed . Using scalar diffraction theory6 and paraxial approximation , the transmission of each of the modulated layers can be described by a Fourier series, t(x) = >A1exp(im ) (1) in which is the spatial frequency of the grating ,and Am represents the amplitude of each diffraction order , which can be , depending on the sinusoidal profile of the modulated layers, written as A, = rtJ,(ç), (2) where m(P)5 the mth-order Bessel function of the first kind and ço is the amplitude of the phase modulation . Following the notation of song et al 61the set of discrete values of the ampliude of the diffraction orders can be, for each of the modulated layers, expressed, 3AJJ = iJ(ço (3) in which j is the layer position .…”