Adaptive optical networks using photorefractive crystals

Adaptive optical networks using photorefractive crystals.

The capabilities of photorefractive crystals as media for holographic interconnections in neural networks are examined. Limitations on the density of interconnections and the number of holographic associations which can be stored in photorefractive crystals are derived. Optical architectures for implementing various neural schemes are described. Experimental results are presented for one of the...

Adaptive optical coherence-domain reflectometry using photorefractive quantum wells

Adaptive optical-coherence-domain reflectometry (OCDR) is performed by use of an adaptive interferometer and homodyne detection. The adaptive element of the interferometer is a photorefractive quantum-well device in a two-wave mixing geometry. The mixing self-adaptively maintains constant relative phase between the signal and reference waves and dynamically compensates gross movements of the sa...

Data Storage and Retrieval using Photorefractive Crystals

Image Enhancement in Coherent Optical Amplification by Photorefractive Crystals

In this paper, a model of two-wave mixing in the photorefractive crystal, which takes account of the difference in spatial frequency in a beam, has been built to study the image enhancement effect in coherent optical amplification. Based on the theoretical analysis of the model, the gain distribution for each pixel in the signal beam has been obtained. It shows that the unevenness of the gain i...

Optical limiters using photorefractive nonlinearities

The ability of photorefractive crystals such as barium titanate and strontium barium niobate to record spatially phase shifted real time holograms with high diffraction efficiency is the basis of many new optical devices involving coherent amplification. Some examples are unidirectional ring resonators, passive phase conjugate mirrors and coherent image amplifiers. 1 While in the past, most att...