共查询到19条相似文献,搜索用时 562 毫秒
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报道了中心对称光折变晶体与线性电介质界面表面波的形成及能量变化. 通过调节传播常数和波导参数的方法,可以得到非局域、振荡、局域三种类型的表面波. 波导参数和传播常数之差大于阈值时,线性电介质和中心对称光折变晶体界面可以形成局域表面波. 波导参数为正值时,局域表面波主要聚集在中心对称光折变晶体内,随着传播常数的增大,波能量随之单调递增,表面波可以稳定传播. 在给定的条件下,调节决定非线性作用强度的可变参量可以控制局域表面波模的阶数和传播波形.
关键词:
非线性光学
中心对称光折变晶体
表面波 相似文献
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光折变效应和带输运模型 总被引:1,自引:0,他引:1
由于光折变效应的光学非线性与光强无关,因而在低功率激光作用下也会产生显著的光学非线性效应.同时光折变效应具有非局域响应性,这导致光耦合的光能不可逆转移.这为通过非线性作用放大信号光提供了一种新途径.由于这些特性,自1966年发现光折变效应以来,它一直是非线光学领域内较为后跃和引人注目的研究课题,其应用也十分广泛.本文介绍了描述光折变效应的Kukhtarev带输运模型,并从Kakhtarev方程出发讨论了在稳态条件下的光折变性质,说明光折变效应的起因. 相似文献
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各向异性光折变光开关的原理 总被引:6,自引:4,他引:2
提出了利用光折变的各向异性衍射特性在单块LiNbO3 晶体中建立光折变 2× 2开关组件的方案。为减少记录的各光折变全息组件之间的串扰 ,采用局域热固定。基于衍射效率公式 ,分析最佳衍射效率时入射光强比和写入角之间的关系。所建立的光开关具有小型化和垂直的输入 /输出的特点。 相似文献
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光折变介质中空间光孤子自弯曲现象研究 总被引:1,自引:0,他引:1
光折变非线性介质在外加直流电压时会引起介质内部电荷移动,而移动后的电荷又会导致空间电荷的扩散效应,从而产生非局域非线性现象。从理论上研究了具有流动和扩散非局域非线性的光折变晶体中所支持的空间光学孤子的传播行为。应用等效粒子近似方法分析了这类介质中(1 1)维空间光学孤子动力学行为,得出孤子运动"加速度"显式解。孤子的有效"加速度"决定于孤子参量和光折变非局域参量。所得的解析结果可在一定参量范围内直接用来计算孤子的传播轨迹。对孤子在光折变非局域非线性作用下的传播动力学行为做了仿真模拟,数值模拟结果与理论分析结论符合得很好。 相似文献
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This paper reports that when an intense extraordinary-polarized laser beam
illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is
formed to be a thermal-like light source with a long correlation time and wide
spectral bandwidth. The experimental results of the first- and second-order
double-slit interference with such photorefractive fanning light source, can be
understood with the theoretical simulation in terms of Hanbury-Brown and Twiss
effect. 相似文献
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理论分析和实验观测了非相干背景光辐照下掺杂LiNbO3晶体中的二波耦合,发现非相干背景光能够在很大范围内灵活有效地控制信号光增益,抑制扇形效应,提高信噪比,缩短光栅的建立时间.入射光光强比一定时,适当地增大背景光光强可以使光栅响应时间减小一个数量级.尤其对于抽运光光强远大于信号光光强的情况下,上述作用更为明显.
关键词:
光折变
二波耦合
非相干背景光 相似文献
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M.H. Majles Ara SR. Hosseini M.H. Rezvani M. Abolhassani 《Journal of Physics and Chemistry of Solids》2011,72(11):1367-1372
In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO3 photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering. 相似文献
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光折变两波耦合对光扇开效应的抑制作用 总被引:4,自引:0,他引:4
以多个两波耦合(TWM)相位栅模型建立了考虑光扇开效应后的动态两波耦合方程,通过数值求解揭示了在大信号两波耦合对光扇开效应的抑制作用和在小信号下光束扇开损耗对两波耦合影响的规律,并进行了相应的实验研究。 相似文献
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In signal beam amplification by two-beam coupling in BaTiO3 photorefractive crystals, beam fanning in the direction of the amplified signal reduces the signal-to-noise ratio (SNR). The dependence of the SNR and the signal beam gain on the crystal orientation are analysed using a HeNe laser. It is found that orientating the crystal for maximum gain gives poor signal-to-noise ratio. A compromise has to be made between the SNR and high gain for optimum signal amplification. 相似文献
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The simultaneous presence of beam fanning and anisotropic conical scattering hinders the exact measurements on anisotropic conical diffraction. In this paper, a method is described for the measurement of diffraction efficiency of the gratings responsible for anisotropic conical scattering in a photorefractive BaTiO3 crystal. Dependence of diffraction efficiency on the angle of incidence of the incident beam and the build-up processes of beam fanning and anisotropic scattering have been studied. 相似文献
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The characteristics of a new high-gain photorefractive polymer composite with a PNP chromophore are investigated. Competition between beam fanning and two-wave coupling (TWC) is predicted and verified experimentally. The intensity dependence of TWC gain is studied. Higher diffraction order and forward phase conjugation in a TWC geometry are observed and explained. 相似文献
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A new method of one-way image transmission through a thick dynamic distorter without the need for a reference beam or four-wave mixing is demonstrated. In this method there are only one object beam and one sampling beam. The response time of the photorefractive crystal must be much longer than the fluctuation period of the dynamic distorter. Thus the crystal responds only to the time-averaged intensity pattern of a rapidly varying object beam. The images, reconstructed with high fidelity, are picked up through the photorefractive fanning effect. 相似文献