Hideshi Yokota

Photorefractive two-wave mixing between phase-modulated beams

Abstract Photorefractive adaptive interferometer is based on the two-wave mixing between phase-modulated beams. A theoretical analysis of photorefractive two-wave mixing between phase-modulated beams is presented. The beam coupling effect and the depletion of all beams (two incident beams and respective diffraction beams) are considered. The experimental results obtained for Bi 12 SiO 20 (BSO) crystal are given.

Fabrication of BGO and BSO films for image recording

Silver halide photographic plates and photosensitive polymers have been utilized for the holographic recording. These materials are available only for recording of still pictures and require complex developing processes and a relatively long time for recording and reproduction of the image. As an alternative, image recording using bismuth silenite compounds has been researched. The BSO and BGO single crystal bulk samples have been used for these studies. We aimed to fabricate BGO and BSO films appropriate for image recording. Films have merits in device integration and mass production. The process condition to obtain a good crystalline film was studied. The film with crystalline phase only was obtained at the substrate temperatures above 200C.

In-situ ellipsometric study of growth of Au thin films

We have equipped an ion assisted deposition system with a rotating-analyzer ellipsometer (RAE) for in-situ monitoring of the deposition process. We propose the optimum conditions for the SiO2/Si substrate system for observation of growth processes of Au film deposition. The deposition of Au films on optimized silicon oxide substrates was observed in- situ using the RAE. The growth curves for Au films were different from those for continuous layer growth in the initial stage. The critical thickness at which the growth became continuous layer growth varied with the irradiated current density of Ar ions. The ion-current density for the minimum critical thickness of Au films has an optimum value of around 100 (mu) A/cm2. The initial stage of Au growth before continuous layer growth occurred was analyzed using the Maxwell-Garnett theory and semi-quantitative agreement was obtained between the experimental and calculated results.

New optical resonators suitable for low-gain large-aperture laser medium such as chemical oxygen-iodine laser (COIL)

The three types of laser resonators are newly proposed for the low gain, large aperture lasers such as COIL. The calculation clearly show the usefulness of these resonators.