Diarylethenes are known as thermally stable photo-chromic compounds, particularly of which diarylethene derivatives having bithiophene as the side groups undergo the great change in the π-electron conjugation length between the open-form and closed-form upon their photo-isomerization. Consequently, the ionization potential (Ip) is expected to change between both forms. In this paper, we have applied the difference of Ip between these two forms for controlling the hole injection from a metal electrode to an organic film. We have succeeded in demonstrating the photo-switch of the injection current on the order of sub-miliampare upon photo-isomerization by inserting a thin film of diarylethene derivative in-between metal and organic charge transport layer.

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We have been studying the characteristics of laser dye transfer printing which produces continuous tone images with high resolution. This paper describes the priniting experiments and numerical calculations to clarify the transfer mechanism of a color dye in the ink layer, which dominates the characteristics of tone reproduction.
We have observed the increasing in gamma of tone reproduction with thicker ink layers. We have confirmed that the dye in the bulk of the ink layer was transferred, using the ink sheet with a laser light absorbing layer and two co1or dye layers on a substrate. From these experimental results, we have introduced the simple model on the dye transfer process. Simulation results almost agree with the characteristics of tone reproduction which depend on the thickness of the ink layer.

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Photorefractive materials have many potential photonic applications, including holographic optical data storage and real time image processing. Recently, the photorefractive polymers has emerged, offering wide structural flexibility, easy processability, and low cost. The requirement for photorefractivity are charge generation, transport and trapping and the electro-optic effect.
Charge generation and transport phenomena has been studied eagerly because of their practical importance in electrophotography. These have resulted in a considerable level of fundamental understanding of the relationship between the structure of these materials and the electronic properties. This understanding will lead to the development of many new and improved materials for photorefractive polymers. The purpose of this paper is to review the organic photorefractive materials and their application for holographic memory. Firstly, the mechanism of formation of the internal field by carrier transport is described. Then, no applied field writing to photorefractive materials is discussed. The following section describes the electro-optic effect in organic materials. Finally, the application for photorefractive memory and the measurement method of photorefractive effect are described.

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Reversible phase change optical recording material with a new quartenary system of Ag-In-Sb-Te, having high sensitivity and high erasability, has been developed.
Furthemore, applying the Ag-In-Sb-Te system to rewritable compact disc (CD-ReWritable; CD-RW), high performance comforming to Orange Book Part III which is the CD-RW standard was achieaved for the first time in the world.

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