基于量子存储机制实现光学信息卷积操作的研究

提出了一种利用量子存储机制进行相干光学信息处理的技术,在4f成像系统的像面上可以实现信号光和读取光之间的卷积运算。实验证明了通过基于电磁感应透明(EIT)效应的光脉冲存储和读取过程实现光学信息卷积操作的可行性。该研究结果为基于量子存储机制进行相干光学信息处理提供了理论和实验依据。     

2f光电混合匹配滤波相关识别研究

提出一种光电混合匹配滤波相关识别方法,只用一个空间光调制器实现了匹配滤波相关识别。利用计算机完成匹配滤波器的设计以及匹配滤波器与输入目标频谱的卷积运算,根据最小欧氏投影编码原理将卷积结果转化为空间光调制器可以显示的灰度信号,再通过2f光学傅里叶变换系统,得到相关识别结果。实验结果表明,该方法可以得到明显的相关点,同时可以避免传统VLC中匹配滤波器的精确复位问题,而且该系统还可以应用于联合变换相关识别。     

单通道光学相关实现击中与否运算

给出了一种单通道光学相关实现击中与否运算的算法和光学装置，此法基于形态学中的腐蚀运算和光学相关的关系及阈值操作，在非相干光学相关器中，将前景结构核元素编码为１，背景结构核元素编码为ａ（ａ满足一定条件），只需用原图像与前景和背景结构进行相关，然后对相关结果取阈值的Ｋ（前景结构核元素的像素数）即可得到击中与否运算，击中与否运算可以光学并行一步实现。     

大气湍流下光学平面面形的估计

针对大气湍流环境下光学元件平面面形PV值测量这一问题。首先建立了一种大气湍流下斐索干涉仪的模型,通过该模型得到1000张干涉条纹图像;然后提出了一种基于卷积神经网络估算PV值的方法,将干涉条纹图像作为卷积神经网络的输入,利用卷积神经网络提取图像的特征信息,得到PV值;最后将得到的结果与ASTM计算得到的结果、相位解包裹得到的结果以及BP神经网络得到的结果进行对比,发现利用卷积神经网络的方法偏差为2.25×10^-4λ,较ASTM、相位解包裹以及BP神经网络得到的结果偏差更小。实验结果表明此方法具有抗干扰性强、精度高、运算快的优点,是一种有效的抗大气湍流影响的光学检测方法。     

用于图像高压缩比编码的方向滤波器的光学实现

本文针对光学与数字技术结合的实现图像高压缩比编码的一种方案——方向滤波方法提出利用补偿滤波技术来保持图像边缘信息,从而利用光学滤波技术实现数字滤波运算,给出高达30:1的高压缩比编码结果.     

光学信息处理讲座 第二讲 半色调方法实现非线性变换

一、引 言 光学信息处理系统具有二维、并行、高速地完成傅里叶变换、相关和卷积等线性运算的能力.在典型的光学处理器以及低功率的情况下,除非使用特殊的技术,一般只能实现线性运算.但是,许多信息处理的应用又要求对数据进行非线性运算.过去,非线性变换主要是通过数字方法实现的.现在已经使用了多种技术来实现光学非线性运算(变换).最方便的方法是利用胶片特性曲线的非线性,实现非线性变换.例如,对数变换[1],密度切片的提取[2]等. 可饱和吸收体以及在某些情况中的光学反馈,也是实现非线性光学运算的重要途径[3,4].由于介质的非线性光学效应…     

多值神经网络改进模型及其光学实现

本文提出一种改进的光学神经网络模型,并利用空间光调制器PROM构成的光学系统实现了这种模型的联想记忆运算.计算机模拟和实验结果表明,改进模型提高了光学神经网络的识别能力,并在—定程度上提高了存贮容量.     

真值表查询式光学符号替换

本文提出了一种新的符号替换光学处理方法.采用互补编码和地点寻址的真值表查询,构造了一种可进行返回运算的全加数字处理器.利用由液晶光阀构成的行逻辑器件对这一符号替换系统进行了实验验证并给出了实验结果.     

基于菲涅耳波带板扫描全息术的光学层析成像

基于光学扫描全息术原理和编码孔径层析成像技术,提出了一种三维物体层析成像技术——菲涅耳波带板扫描全息术。该技术通过将物体的光强分布函数与菲涅耳波带板的光强分布函数进行卷积运算来得到物体的扫描全息图,通过相关解卷积的方法来进行扫描全息图的数字重建。依据该技术原理设计了实验系统,系统结构简单紧凑,具有三维物体层析成像功能。提出用数字高通滤波器来减少重建图像的背景噪声。计算机仿真及对实物的扫描记录和重建实验结果表明,该技术原理正确,用于三维物体层析成像是可行的,用数字高通滤波的方法提高重建图像的对比度是有效的。     

颜色可调假彩色化新方法

本文提出一种颜色可调的密度假彩色编码的新光学方法.该方法是在光学相位调制密度假彩色编码方法的基础上,利用白光系统中双光栅的衍射效应和狭缝滤波技术,实现颜色可调的密度假彩色编码.给出了详细的理论分析,实验验证和实验结果.实践证明这是一种实用价值很高的方法.     

All-optical NOT and XOR logic operation at 2.5 Gb／s based on semiconductor optical amplifier loop mirror

All-optical XOR and NOT logic operations based on semiconductor optical amplifier loop mirror (SLALOM) aresimultaneously demonstrated theoretically and experimentally. Based on a segmented semiconductor optical amplifier model, the all-optical logic operation process is simulated theoretically. In an experimental study, 2.5 Gb/s all-optical XOR operation was achieved in the output port of SLALOM, while all-optical NOT operation was achieved in the input port through a circulator at the same time.     

Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.     

Transient and steady state analysis of micro ring resonator array based photodetector in optical communication wavelength (linear and nonlinear operation)

Array of micro ring resonators based optical photodetectors is introduced and evaluated in this paper to operate in optical communication windows for broad band situation. In this work, we introduced an array of resonators to engineer the transfer function of the detector for broad band operation as well as very sharp edges. The electron and photon transport in the proposed structure is modeled based on rate equation and then transient and steady state behavior are extracted. Finally nonlinear operation added to the model and its effect on spectral behavior as well as transient operation is investigated.     

应用四元数方法对光存储光学系统的建模

光存储中的光学系统是一种非同轴光学系统，其中各个光学元件的设计位置与装配精度是保证系统光线正常传输并获得准确信号的前提。四元数方法是一种可以方便地描述空间光线的传输计算与坐标变换的数学方法。通过将四元数引入到光学头光学系统的建模中，使用四元数法表征非同轴光学系统的传输方式，并给出建立光学元件的设计、安装参数与聚焦光斑、读出光斑之间关系的流程图。据此模型对各个独立的研究对象进行分析的结果，对光存储中光学系统的设计与生产装配工艺的制定有指导意义；同时,以此模型分析物镜的连续运动对光斑和读出信号的影响，对光学头中的可执行机构力矩器的设计有实践作用。     

Improving the stability of distributed-feedback tapered master-oscillator power-amplifiers

We report theoretical results on the wavelength stabilization in distributed-feedback master-oscillator power-amplifiers which are compact semiconductor laser devices capable of emitting a high brilliance beam at an optical power of several Watts. Based on a travelling wave equation model, we calculate emitted optical power and spectral maps in dependence on the pump of the power amplifier. We show that a proper choice of the Bragg grating type and coupling coefficient allows optimization of the laser operation, such that the laser emits a high intensity continuous wave beam for a wide range of injection currents.     

Remotely Pumped Hybrid Amplifiers for Extended Bidirectional Passive Optical Networks

In this contribution, we optimize design parameters of hybrid optical amplifiers utilizing distributed Raman amplification in transmission fiber and gain of discrete, remotely pumped erbium-doped fiber amplifier (EDFA) for wideband, bidirectional operation in metropolitan area networks (MAN). The design is based on an application of a numerical model, which takes into account pump-to-pump and signal-to-signal interactions and generation of amplified spontaneous emission in the Raman amplifier and solves the standard rate-propagation equations in an erbium-doped fiber (EDF). We predict 12 dB gain across 72 nm of optical bandwidth with gain ripple better than 10%. The recently proposed serial topology of EDFA is considered; this enables the wideband, bidirectional operation of a hybrid amplifier with only two pump laser diodes emitting in the 1430 and 1480 nm bands.     

Enhanced single-fundamental LP01 mode operation of 650-nm GaAs-based GaInP/AlGaInP quantum-well VCSELs

Minimal optical attenuation of plastic (polymer) optical fibres (POFs) corresponds to the 650-nm wavelength. Currently the GaInP/AlGaInP quantum-well (QW) oxide-confined (OC) vertical-cavity surface-emitting diode lasers (VCSELs) are undoubtedly the laser devices most suited to be used in 650-nm POF optical communication, for which the stable single-fundamental-mode LP₀₁ emission (SFM) is definitely the one most desired. In the present paper, the comprehensive fully self-consistent VCSEL model is used to examine mode selectivity of the above VCSELs. An increase in the VCSEL active-region diameter leads to a gradual modification of the current injection into this region and subsequent carrier radial diffusion within it before their recombination, which is followed by an essential transformation of active-region optical-gain profiles deciding upon an excitation of successive transverse modes. In standard arsenide OC VCSELs, SFM operation is usually limited to relatively small active regions. But for a room-temperature continuous-wave operation of the GaInP/AlGaInP VCSELs, the fundamental LP₀₁ mode remains surprisingly the lowest-threshold one up to relatively large active regions of 9-μm diameters. Nevertheless, in such VCSELs, thresholds of many LP modes become very similar to one another, which leads to their relatively poor mode selectivity and an unwanted multi-mode operation for higher output powers.     

回转椭球反射镜的检验与检测仪器的设计

本文介绍了根据椭球光学性质研制的FJG-1型椭球反射镜检测仪。它为检验回转椭球反射镜建立了面积有效率、光轴偏移量、f_1值允差与反射率四项技术指标,并给出了检测仪的设计原理与操作方法。最后对仪器的误差及运行效果进行了分析。     

光学读出非制冷红外成像技术的光学灵敏度分析

不同于传统的非制冷红外成像技术,提出了基于微电子机械系统(MEMS)的新概念光学读出非制冷红外成像技术。它的光学读出系统基于空间刀口滤波原理,具有高灵敏度、高分辨率和高抗震性等优点,但同时也受到了反光板的弯曲变形、粗糙度等复杂因素的影响。在大量实验数据的基础上,利用夫琅禾费近场衍射理论,建立了复杂因素下光学灵敏度的理论分析模型,详细分析了刀口滤波位置、反光板的长度、曲率半径、粗糙度、LED光源的强度以及扩展宽度等对光学灵敏度的影响,并提出了通过极限操作使系统的光学灵敏度最大化的光学优化方法。     

一种条纹变像管静态电子光学聚焦特性数值模拟

 对ICF实验中条纹相机的重要组件变像管的工作过程进行了介绍,建立了其内部电子光学系统模型,对其静态电子光学特性进行了数值模拟。模拟软件采用ANSYS,数值计算基于有限元数值计算方法,并利用哈密顿原理求解泛函,在控制计算精度的基础上,得出了该电子光学系统的内部静电场分布和轴上电位分布,同时对静态条件下的电子轨迹进行了模拟计算。结果显示了与理论解析结果很好的相似性,同时初步探索了电极尺寸及电压参数对成像的影响。结果表明,电压参数的改变对光电子成像的影响要更大一些。