光擦除双光束耦合多级光探测器的研究

基于光擦除和双光束耦合的基本原理,提出了一种多级光探测的方法。用带导模型和合波方程建立了理论公式。用三块Ge:KNSBN晶体和He-Ne激光进行了实验演示。理论分析与实验研究均表明所提出的方法是可行的。     

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.     

球形壳层介质的光散射

本文以球形壳层介质为模型，根据电磁理论，求出了球形壳层介质散射系数的解析表达式。并在小颗粒近似条件下，给出了近似解及等效偶极矩。最后与实验结果进行了比较。     

硫化砷非晶态波导光阻断效应的机理研究

在实验研究了As₂S₈和掺杂As₂S₈薄膜波导光阻断效应的基础上,讨论了反常电子组态的形成机理和转移机理,提出了光阻断效应切断过程和回复过程的动力学模型,数值分析结果与实验数据十分符合,理论预期与实验现象一致,表明该模型抓住了光阻断效应的基本特征,揭示了过程本质,反映了实验现象的内在机理. 关键词： 光波导技术 硫属化合物玻璃 光阻断效应 动力学模型     

孤子源啁啾对光孤子传输的影响以及消啁啾的方法

本文提出了一种孤子源非线性啁啾的模型,利用解析和计算机模拟的方法从理论上分析了孤子源啁啾,特别是非线性啁啾对孤子传输的影响,并讨论了消啁啾的两种方法-正色散光纤消啁啾法和Fabry-Perot光谱窗消啁啾法,实验结果与理论分析基本一致.     

光抽运信号的理论分析

在原子辐射跃迁原理的基础上,依据光磁共振实验的基本实验现象建立简化模型,给出光抽运过程中跃迁速率方程,理论计算了光抽运信号光强随外场变化关系以及粒子跃迁弛豫时间随外场的变化关系,理论计算结果与实验符合.     

光发射模块的实现及直线感应加速器注入器的模拟

本文研究开发直线感应加速器的光发射模块,并验证该模块的正确性.首先建立光发射模型,该模型确立阴极参数和入射激光与宏粒子初始值间的关系,并将该模型实现到代码中;其次,根据实验参数建立注入器模型,模拟光阴极的发射过程;最后,将模拟结果与实验结果比较,发现模拟的发射电流与实验电流吻合,发射度与理论分析一致,验证了模拟的正确性.     

GaAs半导体中三光子吸收的研究

本文利用全量子理论推导了半导体中多光子吸收跃迁速率的一般表达式。对各种模型计算了本征GaAs在λ=2.06um下的三光子吸收系数。实验上采用非线性光电导和非线性光透射技术,测量了GaAs中三光子吸收系数。     

离子交换LiNbO_3:Fe平面光波导中两波混合的研究

本文利用耦合波理论分析推导了单模平面光波导中两波混合的耦合波方程和弱相干光放大率的表示式.并且,在LiNbO_3:Fe单模平面光波导中进行了两波混合的实验研究,得到了与理论分析相符合的结果.     

液体中光击穿所激发声场的方向性研究

从液体中光击穿所激发声场的柱体模型和靶盘模型出发,运用声学基础的理论原理,提出了等离子体椭球模型,对光击穿所激发声场的方向性进行了理论研究.通过MATLAB仿真得到此声场的方向特性图,进而分析和比较了能量不同、照射区域大小不同的激光束所激发声场的方向性.研究表明等离子体椭球模型更符合实验情况.     

Holographic read-only memory

We describe the three-dimensional holographic optical disc system for application as read-only memory. Several systems design issues are discussed including imaging optics, storage density, readout rate, and the alignment servo system. We demonstrate 40 bits/m² surface density and pixel-matched holographic data readout from a 12 cm disc spinning at 600 RPM.     

Pit Depth and Width Modulation Multilevel Run-Length Limited Read-Only Optical Storage

When the techniques of integrating the variation of the conventional DVD,the high-density multilevel run-length pit depth and width simultaneously are adopted to limited read-only optical storage method is achieved. The dynamic range of readout signal is greatly enlarged in comparison with keeping one parameter varied, and the recording levels number can be obviously increased. The discs can be manufactured using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs. Experimental results show that eight-level read-only optical disc can be realized and the capacity can be increased to 20 GB.     

Analysis of differential phase detection signal of a novel multi-level read-only disc

To improve the tracking servo performance, a novel signal waveform multi-level （SWML） read-only disc realized on the digital versatile disc （DVD） platform is presented. The characteristic of the differential phase detection （DPD） signal of the SWML read-only disc is analyzed both in theory and experiment. The amplitude of the DPD signal of the SWML read-only disc in an open tracking servo loop is about 2/3 of that of the DVD read-only disc. The uniformity and symmetry of the DPD signal of the SWML read-only disc are similar to those of the DVD read-only disc and better than the former multi-level run-length limited （ML-RLL） read-onlv disc.     

Effect of amplitude modulation on the read-out signal in an optical disc system with a residual aberration

We conducted a numerical calculation for the point spread function and the variation of the read-out signal in optical disc systems using several apodizing filters, taking into account a spherical aberration and the variation in the bump shape. Based on calculations using the scalar diffraction theory, we are able to determine the best bump size and shape giving the maximum read-out signal for each incident beam modulated by an apodizing filter. This work facilitates the fabrication of high density optical disc systems with a spherical aberration and can then be applied to a real optical disc system like a commercial digital video disc (DVD) system.     

Surface optical phonon—assisted electron Raman scattering in a semiconductor quantum disc

We have carried out a theoretical calculation of the differential cross section for the electron Raman scattering process associated with the surface optical phonon modes in a semiconductor quantum disc.electron states are considered to be confined within a quantum disc with infinite potential barriers.The optical phonon modes we have adopted are the slab phonon modes by taking into consideration the Frohlich interaction between an electron and a phonon.The selection rules for the Raman process are given.Numerical results and a discussion are also presented for various radii and thicknesses of the disc,and different incident radiation energies.     

近场记录光盘的写入能量的研究

近场记录光盘是一种新的光盘记录技术,它有二个特点：（１）极高的记录密度;（２）很高的寻道速度。本文介绍了近场光盘技术的特性;提出了近场光盘记录技术中动态条件下读写中的写入能量地头盘间的能量传输问题进行了仿真计算。     

相变光盘分离式光学头设计

光学头是光盘存储系统的核心器件，分离式光学头是把聚焦物镜和光学头的其他部分分离开来，以降低光学头可动部分的重量和体积，提高光学头的飞行速度，实现快速存取的目的。本文设计的相变光盘直接重写分离式光学头．具有结构简单，信号检出方便．易于装配等特点。     

A new tracking error detection method using amplitude difference detection for signal waveform modulation multi-level discs

The sub-land/sub-pit affects the characteristic of the tracking error signal which is generated by the conventional differential phase detection (DPD) method in the signal waveform modulation multi-level (SWML) read-only disc. To solve this problem, this paper proposes a new tracking error detection method using amplitude difference. Based on the diffraction theory, the amplitude difference is proportional to the tracking error and is feasible to be used for obtaining the off-track information. The experimental system of the amplitude difference detection method is developed. The experimental results show that the tracking error signal derived from the new method has better performance in uniformity and signal-to-noise ratio than that derived from the conventional DPD method in the SWML read-only disc.     

Theoretical and experimental analyses of recording mark microstructures in signal waveform modulation optical disc

In this paper,we propose a dynamic mastering process model for signal waveform modulation (SWM) optical disc.To form the ideal microstructures and solve the problems in the SWM master manufacturing process,we use this model to simulate the three-dimensional mark profiles in the SWM read-only disc.The simulated micro-patterns of recording pits and lands are employed to optimize the writing strategy and provide a quantitative basis for manufacturing the sub-pits and sub-lands.The simulation mark profiles are compared with the experimental ones,which are produced with the optimized writing strategy parameters.Comparison results demonstrate that the simulated profiles are highly consistent with the actual ones.     

高精密运动工作台控制系统的设计与研究

设计并研制了用于母盘刻录机的高精密运动工作台及其控制系统。工作台控制系统采用线光栅作为工作台位移检测工具。采用数字位置环和模拟电流环组成双闭环随动系统,其中位置控制器是带有速度前馈和加速度前馈的数字PID伺服滤波器。实验结果表明,该系统可以满足母盘刻录机的要求。