Applications of photorefractive crystals

Abstract

The main suggestions in practical applications of dynamic photorefractive holographic recording for interferometry, processing of 2D pictures, operations with laser beams, and holographic memory systems are reviewed. Specific photorefractive techniques underlying these applications, and in particular, methods of continous and nondestructive hologram reconstruction, nonlinearities in recording mechanisms, and basic limitations due to geometrical factors, Bragg regime of diffraction, and optical noise are considered in detail. The paper is preceded by two introductory sections devoted to fundamentals of dynamic holography and phase conjugation in volume media, and to specific features of' recording and reconstruction of the photorefractive holograms.

Ultrasound-modulated optical tomography at new depth

“…This AC field was voltage-amplified by 60 dB (609E-6, Trek) and applied across the PRC, with which we measured the highest two-wave-mixing gain through thick diffused media (all else being identical). 29 The unmodulated-light power transmitted through a 6-cm thick phantom (μ…”

Выходные характеристики смешанных голограмм в кристалле Bi-=SUB=-12-=/SUB=-TiO-=SUB=-20-=/SUB=- среза (110). Теория и эксперимент

“…Эти кристаллы применяются (см. обзор [4]) при раз-работках оптических корреляторов, фильтров новиз-ны, устройств для выполнения оптических логических операций, при совершенствовании оптических микро-скопов [5] и т. п. Известно, что для эффективного функционирования голографических элементов, выпол-ненных на базе кристаллов силленитов, необходима оптимизация условий считывания сформированных в них голографических решеток. Такая оптимизация мо-жет быть выполнена путем выбора значений азиму-та линейной поляризации считывающего голограмму пучка, при которых для фиксированных углов про-странственной ориентации кристалла, называемых ни-же ориентационными углами, достигаются максималь-ные значения дифракционной эффективности голограмм.…”

Making of a nonlinear optical cavity

“…Even if it brings some similarity with the optical Kerr effect, the photorefractive response is quite different and more complex because charge transport processes and interband transitions are involved in it [4][5][6][7]. Let us be somewhat more concrete.…”

“…A photorefractive oscillator (PRO) [1] is a special type of nonlinear optical cavity [2,3], a term used to generically refer to optical resonators that contain a nonlinear medium (a material exhibiting some kind of nonlinear optical response); in the case of the PRO the nonlinear medium being a photorefractive crystal (PRC) [6,7]. Some PROs find applications in phase conjugation or gyroscope, among many others [6,7].…”

“…Some PROs find applications in phase conjugation or gyroscope, among many others [6,7]. However, our interest is not on the applicability of the device: We are interested in the study of the PRO as a nonlinear optical cavity, i.e., we use it as an experimental model of such cavities.…”