Showing papers by "Osamu Matoba published in 1995"
TL;DR: In this article, a novel method of modifying photorefractive waveguides in a lithium niobate crystal by a guided beam was investigated experimentally and numerically, and it was shown that the transmitted power or peak intensity of the probe beam decreases exponentially as a function of total exposure energy of the modification beam.
Abstract: We investigate experimentally and numerically a novel method of modifying photorefractive waveguides in a lithium niobate crystal by a guided beam. The guided beam with a strong optical power can change the refractive index of the photorefractive waveguide because of the photorefractive effect. The modification of waveguide structure can be utilized for optical dynamic interconnection. Changes of optical characteristics of a probe beam caused by a modification beam are investigated. Experimental results show that the transmitted power or the peak intensity of the probe beam decreases exponentially as a function of total exposure energy of the modification beam. We also numerically analyze the refractive index change caused by the modification beam in the photorefractive waveguide. The numerical results show good agreement with the experimental results.
8 citations
18 Aug 1995
TL;DR: In this paper, the authors present an approach to optical dynamic interconnections for neural networks by simply focusing and scanning a laser beam in a volume of a photorefractive medium and present the optical dynamic characteristics of the PR waveguide.
Abstract: We present our approach to optical dynamic interconnections for neural networks. In this approach we fabricate waveguide structures in photorefractive media by simply focusing and scanning a laser beam. Resultant waveguides with variable index profiles are used for the optical dynamic interconnections. We show the experimental results of waveguide fabrication in a volume of a photorefractive (PR) medium and present the optical dynamic characteristics of the PR waveguide. We propagated the green Ar ion laser light (515 nm) in the photorefractive waveguide repeatedly and observed the variation of the near-field pattern at the end face of a 2 mm-thick lithium niobate (LiNbO3; LN) crystal. The average optical intensity of the guided beam decayed exponentially with respect to the total exposure over the waveguide. It is supposed that the guided beam redistributed or destroyed the charge density field formed by the initial exposure. A numerical analysis based on the beam propagation method and a simple PR waveguide model of this process showed reasonable agreement with the experimental results. This variation of the guided optical power can be used to implement dynamic interconnections for neural networks.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
5 citations