Modification of Photorefractive Waveguides in Lithium Niobate by Guided Beam for Optical Dynamic Interconnection

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.     

光折变晶体中光互联的研究

对光折变晶体中的光互联进行了研究，提出一种利用桥式互泵浦位相共轭器在同一种光路下实现光开关、广播式、合成式及点点式光互联的方法，同时研究了利用光折变两波耦合进行光互联的强度和时间特性     

利用电子俘获材料实现光学IPA神经网络模型

报道用自行研制的ＣａＳ（Ｅｕ，Ｓｍ）电子俘获材料表示互联机重矩阵以实现光学ＩＰＡ神经网络模型，由于ＣａＳ（Ｅｕ，Ｓｍ）的红外激励发光强度与俘获的电子密度及红外读出光强度之积成线性关系，故可用来表示互联权重矩阵以实现光学神经网络，这种互联权重矩阵具有很宽的数值范围，并可以用光学的办法进行快速擦除，重写。     

Optical Associative Memory Based on Double Phase Conjugation Using Bi_（12）TiO_（20） Photorefractive Fi

ＯｐｔｉｃａｌＡｓｓｏｃｉａｔｉｖｅＭｅｍｏｒｙＢａｓｅｄｏｎＤｏｕｂｌｅＰｈａｓｅＣｏｎｊｕｇａｔｉｏｎＵｓｉｎｇＢｉ＿（１２）ＴｉＯ＿（２０）ＰｈｏｔｏｒｅｆｒａｃｔｉｖｅＦｉｂｅｒ￥ＬＩＵＳｈｕｔｉａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ，...     

Optical Learning Neural Network Using a Selfoc Microlens Array for Pattern Recognition

An optical system for learning neural networks with a 2-D architecture was constructed using a Selfoc microlens array. Using this system, we achieved pattern recognition of typed alphabet characters detected directly with a CCD camera. The system learned 4 characters according to a random search algorithm in order to avoid the difficulties and the costs of calculations of learning signals, optical alignments and addressing to the device which display the weight tensors.     

用于光互连的聚硅氧烷波导弯曲损耗

研究了用于光互连的聚硅氧烷多模光波导直接弯曲时弯曲损耗与圆弧曲率半径的关系。用Marcuse的直波导近似法理论计算了其弯曲损耗,理论计算表明弯曲损耗随模阶数的增加而变大,随半径的减少而变大;光在波导中传输时,总弯曲损耗出现阶跃式变化,并且曲率半径大于4 mm时,波导的弯曲损耗小于1dB/cm。用BeamPROP仿真软件仿真了5、10、20mm三种曲率半径下的传输光场情况。利用数字化散射法测量了其弯曲损耗,实验结果显示曲率半径在5～6mm时弯曲损耗值在0.55～0.8dB/cm之间,考虑所制备的聚硅氧烷直波导固有的传输损耗,实验值与理论值基本相符。     

基于层状固定光折变全息的单块光学修正的gamma网络

提出一种利用ＣＯ２激光热固定的层状光折变体相位全息在一块晶体内实现一个固态微小化光学系统的方法理论分析证明利用双面线状激光加热的方案可以形成适合热固定的层状温度分布，初步实验中，在一块ＬｉＮｂＯ３光折变晶体中建立了单级的修正的ｇａｍｍａ网络，由此表明把一个复杂的光学系统微小化组装在单块的晶体中是可行的。     

屏蔽光伏孤子诱导的非线性光波导

从理论上研究了由一维稳态屏蔽光伏孤子诱导的非线性波导,结果表明在加偏压的光伏光折变晶体中,例如铌酸锂,无论是明孤子还是暗孤子都能诱导出非线性波导.推导出了在一般条件和低振幅条件下探测光束满足的波方程.     

聚硅氧烷改性及多模光波导制备

采用含氢聚硅氧烷(HPSO)和二乙烯基苯(DVB)的交联体掺入聚二甲基硅氧烷(PDMS)中,使改性的聚二甲基硅氧烷(M-PDMS)折射率发生1%～1.8%的改变。M-PDMS及PDMS薄膜具有良好的光透射率和低的传输损耗,是低成本制备用于高速芯片间光互连聚合物光波导的理想材料。采用软成型和图案转移法,用M-PDMS及PDMS分别作波导的芯层和包层制备了截面为50μm×50μm,长度大于20cm的聚硅氧烷多模光波导。用数字化散射法测量了所制备波导的传输损耗,测得输入光波长为633nm时平均传输损耗为0.137dB/cm。     

Waveguides induced by grey screening solitons

We investigate the properties of waveguides induced by one-dimensional grey screening solitons in biased photorefractive crystals. The results show that waveguides induced by grey screening solitons are always of single mode for all intensity ratios, i.e. the ratios between the peak intensity of the soliton and the dark irradiance. Our analysis indicates that the energy confined near the centre of the grey soliton and the propagation constant of the guided mode of the waveguide induced by the grey screening soliton increase monotonically with intensity ratio increasing. On the other hand, when the soliton greyness increases, the energy confined near the centre of the grey soliton and the propagation constant of the guided mode of the waveguide induced by the grey screening soliton decrease monotonically. Relevant examples are provided where photorefractive crystal is of the strontium barium niobate type.     

固体激光光折变自适应光外差探测技术研究

依据光折变晶体中自抽运与互抽运相位共轭共存的特性，提出了一种新型的光折变自适应光外差探测系统，并利用相干性较差的固体激光器进行了自适应光外差探测的实验研究。该系统具有结构简单、干扰和外差探测灵敏度高等优点，在光通信、激光雷达等许多领域内都具有重要的实用价值。     

Optical Correlator and Photorefractive Two－wave Mixing Based Neural Recongnition

ＯｐｔｉｃａｌＣｏｒｒｅｌａｔｏｒａｎｄＰｈｏｔｏｒｅｆｒａｃｔｉｖｅＴｗｏ－ｗａｖｅＭｉｘｉｎｇＢａｓｅｄＮｅｕｒａｌＲｅｃｏｎｇｎｉｔｉｏｎ￥ＦＵＸｉａｏｌｉ；ＬＩＹｕｌｉｎ（Ｘｉ＇ａｎＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｓＭｅｃｈａｎ...     

光学神经网络中硬件误差对性能影响的分析

利用统计方法，分析了光学硬件误差对用Ｈｏｐｆｉｅｌｄ神经作联想记忆时出错率的影响，导了系统的误差与错率关第的近似公式，并给出了模拟结果。得到了一定限度的误差对出错率的影响并不显著的的结论，特别坚探讨测器阵列动态范围的要求，可以远远小于其探测到的最大值。这对光学神经网络系统的设计及硬件的选取，具有指导意义。     

光折变自适应光外差探测系统理论研究

首次对光折变自适当光外差探测系统的工作状态进行了较全面分析。给出了系统的最小可探测信号功率和可提供的参考光功率，指出了影响系统特性的关键参数。     

硅衬底上锗硅合金光波导的研制

报道锗硅合金在λ＝１．３μｍ的脊形单模光波导的设计，工艺及测量结果。这种光波导的传播损耗已达０．７ｄＢ／ｃｍ。脊形的高４－８μｍ，宽８－１２μｍ，均和单模光纤芯径相当，此外，其数值孔径在光波导的输入，输出端均能和单模光纤匹配，它已满足硅光集成对光波导的要求。文中最后报道了用这种锗硅合金光波导试制Ｙ分支器，并观察到二支分路输出的单模光斑。     

An Optical Image Encryption Method Using Hopfield Neural Network

In this paper, aiming to solve the problem of vital information security as well as neural network application in optical encryption system, we propose an optical image encryption method by using the Hopfield neural network. The algorithm uses a fuzzy single neuronal dynamic system and a chaotic Hopfield neural network for chaotic sequence generation and then obtains chaotic random phase masks. Initially, the original images are decomposed into sub-signals through wavelet packet transform, and the sub-signals are divided into two layers by adaptive classification after scrambling. The double random-phase encoding in 4f system and Fresnel domain is implemented on two layers, respectively. The sub-signals are performed with different conversions according to their standard deviation to assure that the local information’s security is guaranteed. Meanwhile, the parameters such as wavelength and diffraction distance are considered as additional keys, which can enhance the overall security. Then, inverse wavelet packet transform is applied to reconstruct the image, and a second scrambling is implemented. In order to handle and manage the parameters used in the scheme, the public key cryptosystem is applied. Finally, experiments and security analysis are presented to demonstrate the feasibility and robustness of the proposed scheme.     

非均匀平板波导的色散方程

利用转移矩阵理论分析了任意折射率分布平板波导的传输特性，导出了非均匀平板波导的近似解析色散方程，并指出了ＷＫＢ近似的局限性，数值比较的结果表明，文中所得公式的精确度优于传统的ＷＫＢ方法和其它近似方法。     

多状态,多阈值神经网络模型的光电混合实现

提出了一种采用高分辨率液晶电视（ＬＣＴＶ）实现Ｈｏｐｆｉｅｌｄ神经网络多值算法的光电系统，文章给出了平面多状态，多阈值的全互连Ｈｏｐｆｉｅｄ神经网络模型，并采用该系统对颜色进行了联想和记忆的实验，初步的实验结果可以证实，此种高分辨率液晶电视神经网络系统是可行的。     

分数傅里叶变换光学实现的基本单元

提出一些实现分数傅里叶变换的新型的基本光学单元。这些基本单元仅使用一个透镜和一个菲涅耳衍射，给光学设计增加一些新的可选基本类型，对于给定焦距的透镜，它能完成的分数傅里叶变换是Ｌｏｈｍａｎｎ给出的单透镜结构无法实现。     

双光子光折变介质中非相干耦合光伏孤子族

为了得到双光子非相干耦合光伏孤子族的结果,采用数值模拟方法,对稳态情况下多束互不相干的光束在双光子光伏光折变晶体中的传播进行了研究。结果表明:具有相同偏振和相同波长的多束互不相干的入射光束可在晶体中形成双光子非相干耦合光伏孤子族。当入射光束中仅包含两个分量时,孤子族就转化为光伏孤子对。并用双光子光伏光折变晶体Cu:KNSBN和LiNbO3进行了分析说明。研究结果可为空间光孤子理论的发展提供理论依据。