信息光学 光计算

TP381 2005042805 用细菌视紫红质膜实现多进制数字光学运算=Digital op- tical operation in multilateral system by bacteriorhodopsin film[刊,中]／顾立群(南开大学物理学院．天津(300071)), 陈桂英…／／物理学报,-2004,53(12),-4236-4242 细菌视紫红质(bR)膜对黄光和蓝光的透射具有互补调制特性．由解黄光、蓝光透射光强的速率方程而得到黄光和蓝光的互补抑制透射特性的解析表达式和图示结果。     

细菌视紫红质的动态透射特性及其应用

细菌视紫红质 (Bacteriorhodopsin,简称 b R)是由嗜盐菌中提取出的一种光敏蛋白质 ,它是一种新型的生物光子学材料。我们测量的 b R膜在黄光和蓝光束分别照射下的非线性透射特性表明 ,在光照开始阶段 ,光的透过率随时间延长而增加 ,然后逐渐达到一个稳定值。黄光和蓝光的透过特性的不同是蓝光达到最大透过率的时间比黄光短。 b R膜在黄光和蓝光双光束同时照射下的非线性透射特性的计算结果表明 ,在某一固定蓝光光强 ,蓝光的透过光强随黄光强度的增加而减小 ,甚至变为零。这说明黄光对蓝光有抑制作用 ,即黄光可以调控蓝光的透过率。这一奇异的透射特性可以用做新出现事物滤波器     

基于菌紫质的光开关原型器件研究

本文分析和讨论了细菌视紫红质的饱和吸收特性及互补抑制特性,在此基础上进行了细菌视紫红质光开关的实验研究。研究证明了被激发到M态的细菌视紫红质分子对紫光有较大的吸收,而处于基态的分子则对黄光有较大吸收。随着入射黄光强度的增加,菌紫质对黄光的吸收呈饱和吸收特必,时菌紫质对紫光呈较大吸收,而较强的紫光照射将会使此饱和吸收阈值增加,使得菌紫质对黄光的吸收又增大,从而黄光和紫光表现出互补透射特性。利用紫光和黄光控制菌紫质分子在M态和基态上的分布,我们实现了对不同的波长光和选通或者关闭,即光开关模型。     

菌紫质光致变色吸收特性的二能级理论研究

采用二能级模型(B态和M态)简化菌紫质(bR)光循环过程,建立了菌紫质光致变色吸收特性的数学方程,数值计算了bR膜对570nm单光束和对570nm与412nm双光束的吸收特性.计算表明,bR膜的光吸收特性与入射光波长、入射光强、摩尔消光系数、光密度和M态寿命有很大的关系.bR膜用于光存储时,读出光强和M态寿命是影响bR读出使用时间的两个重要因素.570nm与412nm双光束作用于bR膜时,可以实现以光控光操作,但由于570nm黄光的透过动态范围要比412nm紫光的透过动态范围大得多,因而在实际应用中应以黄光作为信息光,紫光作为控制光.基于bR膜对黄、紫光束的吸收特性,可以将其应用于亮背景滤除、反象器、图象相减、光寻址空间光调制器等光信息处理领域.     

细菌视紫红质用于光子逻辑门的研究

本文对基于细菌视紫红质变种材料D96N的三种基本光逻辑操作进行了研究.随着入射黄光强度的增加,菌紫质对黄光的吸收呈饱和吸收特性,此时紫光的照射将会使此饱和吸收阈值增加.在黄光和紫光对样品的共同作用下,透射光强度会被调制,调制的程度取决于这两束光的相对强度以及被调制光波长.通过观测被调制的525nm检测光强度,我们模拟了几种基本的光子逻辑运算:“非”、“或”和“与”运算.     

细菌视紫红质的自衍射效率与最佳入射角研究

研究了弱光强下细菌视紫红质膜(bR膜)的自衍射特性.给出了弱光强下相干光在bR膜中产生的振幅光栅光强分布模型，并用ysinαx近似表示透射光强分布，结果与实验吻合.给出了不同透射光强y与指数α的对应关系.结果表明，在bR膜及入射光波波长给定的情况下，入射光强越小，对应的α值越大，当入射光强为0.072/T(mW/cm2)时，α等于1.计算出不同入射光强和入射角下的自衍射效率.结果发现，对应于最大衍射效率的最佳入射角为2°.     

光致变色菌紫质薄膜的动态光学响应特性

用二能级光致变色模型,理论分析了菌紫质薄膜在570nm单光束和570nm与412nm双光束作用下光致变色的动态光学响应特性.计算表明,M态寿命越长,入射光强越大,则透过光的响应越快,入射光透过率饱和值越大.在双光束的作用下,可以用570nm的黄光调制412nm紫光的透射光强,实现以光控光操作.根据计算结果分析了bR膜在运动探测应用中的特点.     

非均匀输入图像对基于细菌视紫红质膜的新事物滤波器输出特性的数值模拟

研究了基于细菌视紫红质(bR)膜的新事物滤波器的非均匀输入图像对输出图像特性的影响.与具有均匀光强分布的输入图像相比，在正弦分布的输入图像情况下，输出图像的光强分布不再呈现单调变化，而是出现两个峰值，其中间有较小的光强.bR膜的M态寿命和物体运动速度对输出图像上蓝光光强的分布有一定影响.M态寿命越大，透过的蓝光光强越小，减小的幅度是随着M态寿命的增加而减小，当M态寿命τ>50s时，减小的幅度几乎为零.在相同的入射光情况下，对于输出图像的相同位置，输入图像的运动速度越大，其输出的蓝光光强越大. 关键词： 细菌视紫红质膜 新事物滤波器 非均匀输入图像 输出特性     

细菌视紫红质膜快速光开关的实验研究

建立了“脉冲激光－连续探测光－连续擦除光”的实验系统。在532nm的调Q脉冲激发光和不同波长的连续探测光作用下，研究了细菌视紫红质（BR）膜的光循环过程中的快速响应特性及各中间态的快速光吸收特性。观察到了微秒量级的快速光开关现象，并分析了激发光脉冲作用结束时，各中间态上细菌视紫红质分子的分布。     

BRD96N光调制吸收增强现象的实验研究

通过光谱响应特性实验和记录／读出图像实验，研究了基因变异型细菌视紫红质（BR_D96N）分子膜对单色光的光调制特性.发现BR_D96N分子膜在550nm—600nm范围内对调制光有吸收增强的现象，且对此范围内不同波长的单色光其调制程度有差异.利用曲线拟和方法发现550nm—600nm吸收增强的变化过程分为快过程和慢过程，其对应的时间常数分别为30s和5min.利用强度调制器的吸收强度与图像灰度之间的关系，分析了560nm—600nm范围内出现图像反转的实验现象. 关键词： 细菌视紫红质D96N分子膜 光谱响应 吸收增强现象 图像反转现象     

One-step optical trinary signed-digit arithmetic using redundant bit representations

A simple one-step fully parallel trinary signed-digit arithmetic is proposed for parallel optical computing. This technique performs multidigit carry-free addition and borrow-free subtraction in constant time. The trinary signed-digit arithmetic operations are based on redundant bit representation of the digits. Optical implementation of the proposed arithmetic can be carried out using correlation or matrix multiplication based schemes. An efficient matrix multiplication based optical implementation that employs a fixed number of minterms for any operand length is developed. It is shown that only 30 minterms (less than recently reported techniques) are enough for implementing the one-step trinary addition and subtraction.     

Canonical quaternary signed-digit arithmetic using optoelectronics symbolic substitution

A higher radix based signed-digit number system, such as the quaternary signed-digit (QSD) number system, allows higher information storage density, less complexity, fewer system components, and fewer cascaded gates and operations. An optoelectronics symbolic substitution scheme to handle the parallel quaternary signed-digit (QSD) arithmetic operations is proposed. A conversion algorithm is employed on the QSD numbers to simplify the addition process and reduce the number of the optical symbolic substitution rules. The optical addition operation of two QSD numbers is performed in one-step. An efficient shared content-addressable memory (SCAM)-based optical implementation of the QSD addition/subtraction operations employs a fixed number of minterms for any operand length. The canonical QSD number addition/subtraction scheme requires a significantly reduced number of minterms when compared with a similar previously reported technique.     

Raman Characterization of Pigments in Painted Beams and a Wall Painting Discovered in the San Francisco Church in Santiago,Chile

A material characterization of two artworks discovered in the San Francisco Church, Santiago, Chile, was performed using micro-Raman spectroscopy. Structural painted beams and a wall painting that belong to the same time period, between the end of the 17th and 19th centuries, were analyzed. The cross-section samples of both artworks were characterized and animal protein was identified in the ground layer in both cases. The supporting material of the beams was identified as cypress wood, and a rag paper layer was used as a base for the paint layer, which is composed mainly of a white ground layer on which the color was subsequently added; the yellow pigments are orpiment and chrome yellow; the green color probably arises from a mixture of orpiment, red lead, ultramarine blue, and calcite. A complete analysis of the materials using complementary techniques such as microchemistry and optical microscopy indicates that the mural was painted using a mixed technique and that organic and inorganic pigments were used. The identification of the synthetic pigment ultramarine blue in some blue areas of the wall revealed a modification of the wall painting in the 19th century; dark blue areas resulted from a mixture of indigo, palygorskite, and lazurite.     

Electronic speckle-pattern interferometer using holographic optical elements for vibration measurements

We report a simple, compact electronic speckle-pattern interferometer (ESPI) incorporating holographic optical elements (HOEs) for the study of out-of-plane vibration. Reflection and transmission HOEs provide reference and object beams in the interferometer. The alignment difficulties with conventional ESPI systems are minimized using HOEs. The time-average ESPI subtraction method is used to generate the fringe pattern and remove background speckle noise by introducing a phase shift between consecutive images. The amplitude and phase maps are obtained using path-difference modulation.     

The behaviours of optical novelty filter based on bacteriorhodopsin film

The quality of the novelty filter image is investigated at different intensities of the incident blue and yellow beams irradiating a bacteriorhodopsin (bR) film. The relationship between the transmitted blue beams and the incident yellow beams is established. The results show that the contrast of the novelty filter image depends on the lifetime of longest lived photochemical state (M state). These results enable one to identify the direction of a moving object and to improve the quality of the novel filter image by prolonging the lifetime of M state.     

All-optical time-delay relay based on a bacteriorhodopsin film

Using the property of dynamic complementary suppression modulated transmission of bacteriorhodopsin film, we propose and demonstrate an all-optical time-delay relay in an incoherent light system. The relay can last for a certain amount of time after the switch function of turn off (or turn on) is activated. Furthermore, the delay time can be adjusted by changing the lifetime of the M state and the intensities of blue and yellow beams.     

Continuous-variable quantum key distribution based on photon addition operation

It is shown that the non-Gaussian operations can not only be used to prepare the nonclassical states, but also to improve the entanglement degree between Gaussian states. Thus these operations are naturally considered to enhance the performance of continuous variable quantum key distribution(CVQKD), in which the non-Gaussian operations are usually placed on the right-side of the entangled source. Here we propose another scheme for further improving the performance of CVQKD with the entangled-based scheme by operating photon-addition operation on the left-side of the entangled source.It is found that the photon-addition operation on the left-side presents both higher success probability and better secure key rate and transmission distance than the photon subtraction on the right-side, although they share the same maximal tolerable noise. In addition, compared to both photon subtraction and photon addition on the right-side, our scheme shows the best performance and the photon addition on the right-side is the worst.     

Unified negabinary symbolic arithmetic for addition and subtraction with polarization-encoded optical shadow casting

Conventional algorithms process addition and subtraction in different ways. In this paper, by introducing bipolar carries, a unified negabinary symbolic arithmetic for the two operations can be derived, using only the same six substitution rules. Based on the polarization-encoded optical shadow-casting technique, the encoding and decoding patterns for half-addition, half-subtraction and unified arithmetic are designed, with the fixed LED pattern and separate and simultaneous generation of the multi-outputs. The architecture is simple, programmable, cost-efficient, and the addition and subtraction of multiple pairs of bipolar numbers can be handled in parallel in the same manner.     

偏振全息光栅衍射光场的理论分析

利用介质的光致各向异性和可记录偏振全息光栅,从偏振全息的透射琼斯矩阵出发,运用傅里叶展开法,对记录光不同的偏振态组合情况下,衍射光场的可能出现的衍射级次及其偏振特性进行了理论分析.并以甲基橙掺杂聚乙烯醇膜为例,对各阶衍射光的衍射效率进行了理论计算.