A study of light stimulus propagation phenomena in optical information processing media, liquid crystals

光信息处理介质液晶中光刺激传播现象的研究

基本信息

批准号：
02805037
负责人：
OKUDA Masahiro
金额：
$ 1.28万
依托单位：
University of Osaka Prefecture
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02805037/
关键词：
Nematic Liquid Crystals Light Stimulus Propagation Optical Information Processing Charge Carrier Transport Impurity Ion Neural Computation Nonlinear Pockel's Effect Pattern Recognition 液晶

项目摘要

(a) The mechanism of normally incident photoinduced current transients in homogeneous nematic samples in an applied voltage has been studied theoretically and experimentally. Explicit expressions for the photovoltaic emf are derived using the nonlinear optical Pockel's effect induced by the Freedericksz transition. The current transient is elucidated by the effect of dc field-induced ion drift to electrodes based on an equivalent circuit. The experimental results are completely explained by the present theory.(b) Measurements of discharging current transients in nematic liquid crystals have been made at various applied voltages and temperatures. A well-marked peak in the discharging transient is observed in both nematic and isotropic phase for the first time. Computer simulation based upon a random walk method has been also carried out in order to explore the origin of such an anomalous peak. It is concluded that the occurrence of the anomalous peak is ascribed to a relaxation of an applied-electric-field-induced non-uniform distribution of space charges due to impurity ions incorporated in the liquid crystals.(c) The simulation of visual excitation (SVE) by new effect of nonlinear optical rectification in nematic liquid crystals has been reported. It is shown that this opto-electric structure is naturally similar to the real visual neurotic element. As an example, an optical parallel processing device structure using SVE is proposed for pattern recognition.

（a）从理论上和实验上研究了在施加电压下均匀向列样品中垂直入射光感生电流瞬变的机制。利用 Freedericksz 跃迁引起的非线性光学普克尔效应导出了光伏电动势的显式表达式。基于等效电路，通过直流场感应离子漂移对电极的影响来阐明电流瞬变。本理论完全解释了实验结果。(b)在不同的施加电压和温度下对向列液晶中的放电电流瞬态进行了测量。首次在向列相和各向同性相中观察到放电瞬态中明显的峰值。为了探索这种异常峰的起源，还进行了基于随机游走方法的计算机模拟。结论是，异常峰的出现归因于液晶中掺入杂质离子，导致施加电场引起的空间电荷不均匀分布的弛豫。(c)视觉激发的模拟( SVE）通过向列液晶非线性光学整流的新效应已被报道。结果表明，这种光电结构与真实的视觉神经元自然相似。作为一个例子，提出了一种使用SVE的光学并行处理设备结构用于模式识别。