Abstract

A computational algorithm for analyzing diffraction properties of optical devices, the optical beam propagation method, has suggested a new class of device [stratified volume holographic optical elements (SVHOEs)] by which Bragg regime (thick grating) response can be obtained from a spaced sequence of thin grating layers. The SVHOE device structure consists of a sequence of thin photosensitive holographic recording layers that perform the optical modulation function, interleaved with optically passive buffer layers, i.e., layers that impress no modulation on the light beam but rather allow the diffraction processes necessary for thick grating response to occur. Such devices can emulate distributed gratings in terms of diffraction efficiency and angular selectivity and possess periodic diffraction properties that might serve, for example, as interconnections for optical cellular logic arrays. SVHOEs 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. In addition, the diffraction characteristics are observed to alternate between Raman-Nathlike behavior and Bragglike behavior as a function of buffer layer thickness due to periodic rephasing of the higher diffracted orders with the zeroth and first orders. This in turn leads to an unusual dependence of the diffraction efficiency on, for example, the grating spatial frequency and the wavelength of readout illumination. Experimental implementations of SVHOE structures are described, both with fixed gratings and dynamic reconfigurable media.

© 1988 Optical Society of America