声光器件特性分析及音频声光通信研究

分析了声光效应的基本原理及布拉格效应成立的条件,构建了声光器件特性测试实验装置。对声光器件中布拉格衍射的建立、声光调制的幅度特性及频率特性等基本特性进行了测量分析,对声光模拟信号传输的线性特性和音频频响关系进行了研究。     

力学一题解

力学一题解此题的已知条件完全由图线上得知．设距波源。＝２ｍ处质点的振动表示式为由图１可知，ｙ１＝Ａ／２，ｖ１＜０，则又，则所以因为ｔ１＝１０９／１２０，ｔ２＝９１／８０，即由图２可知，波长λ＝１６ｍ，波传播速度ｖ＝λ／Ｔ＝３２ｍ·ｓ（－１）当ｘ＝２，...     

声光Naman-Nath衍射特性的研究

讨论了液体介质中的超声相位光栅的形成,根据声光相互作用类型的区分标准,在液体介质的超声光栅实验中声光相互作用一般为Naman-Nath衍射;相位光栅可以由声行波和声驻波形成,且形成的各级衍射条纹极大均由相同的光栅方程决定,各级衍射条纹的强度由相应阶次的J2m函数值决定;在此基础上给出了衍射条纹和衍射光强的分布特点.     

~(14)N~(16)O分子X~2Π_(3/2)R(1.5)v=0→1及~(15)N~(16)O分子X~2Π_(3/2)Q(1.5)v=0→1跃迁的FLMR光谱

本文采用法拉弟效应的激光磁共振光谱技术，研究了－氧化氮分子１４Ｎ１６ＯＸ２Π３／２Ｒ（１．５）ｖ＝０→１和同位素分子１５Ｎ１６ＯＸ２Π３／２Ｑ（１．５）ｖ＝０→１跃迁的ＦＬＭＲ光谱，实验给出了样品浓度和信号强度之间的关系及调制磁场强度与ＦＬＭＲ信号强度之间的关系。     

^14N^16O分子X^2П3＼2R（1.5）v=0→1及^15N^16O分子X^2П3＼2Q（…

本文采用法拉弟效应的激光磁共振光谱技术，研究了一氧化氮分子＾１４Ｎ＾１６ＯＸ＾２П３／２Ｒ（１．５）ｖ＝０→１和同位素分子＾１５＾１６ＯＸ＾２П３／２Ｑ（１．５）ｖ＝０→跃迁的ＦＬＭＲ光谱，实验给出了样品浓度和信号强度之间的关系及调制磁场强度与ＦＬＭＲ信号强度之间的关系 。     

声光效应实验研究

介绍声光效应的最新理论进展。采用光栅假设，对各向同性介质中的声光效应作了简要讨论，导出了第m级衍射光的衍射效率公式。研究和介绍一种新的声光效应实验装置。在实验中，应用线阵CCD光强分布测量仪等，通过改变超声波的频率和功率，分别实现了对激光束方向的控制和强度的调制；定量给出了声光偏转量的关系曲线和声光调制测量的关系曲线。实验表明，在布喇格衍射下，通过固定超声波功率，测量衍射光相对于零级衍射光的相对光强与超声波频率的关系曲线，不仅可以计算声速，还可以确定声光器件的带宽和中心频率。     

TEM01模式激光对两能级原子的作用力研究

推导了两能级原子在稳态和小速度一阶微扰近似下的受力矢量方程，并分析表明ＴＥＭ０１模光场以原子的作用力中存在旋涡力，对在大正失谐δ〉〉Ω０〉〉Г和ｚ〈〈ｚ０＝ｋｗ＾２／λ条件下的ＴＥＭ０１模行波和驻波场中原子的受力进行了分析，对行波场，自发辐射对原子运动的影响很大，但在ｒ〈〈λ区域内原子受到横向囚禁力；对驻波场，自发辐射的影响可以忽略，考虑在ｚ方向波长范围内原子的平均受力得到的结论为：在横向，除了有     

百瓦级全固态绿光激光器的实验研究

利用80个20 W的二极管呈五角型阵列泵浦Nd:YAG棒,采用KTP晶体（Ⅱ类相位匹配θ＝90°,φ＝23.6°）腔内倍频、单声光调Q装置、平凹直腔结构,在泵浦电流17.5A、声光调制频率20.4kHz 时获得了平均输出功率为97 W、脉冲宽度150 ns的准连续绿光;分析了泵浦功率密度及晶体内部温度是影响倍频效率的因素,认为此实验中获得高功率的关键原因是对KTP晶体使用了角度调节并加强了水冷.     

二氧化碲非同向声光可调谐滤波器的设计分析

在分析非同向声光可调谐滤波器器件设计理论的基础上，同时考虑声光晶体的双折射和旋光特征，分析和计算了二氧化碲声光可调谐滤波器的超声波极角θａ和入射光波极角θｉ之间的关系以及超声波频率ｆａ和光波波长λ０之间的调谐关系。     

一类一维势场中电子态的研究

研究了在一维势场Ｖ_n＝λｃｏｓ（Ｑn＋ａｎ^ｖ）（０＜ｖ＜１）中运动的电子状态，计算了本征能量和本征态的局域化指数。对Ｑ＝２π／３，系统的能带由三个子能带构成。当λ小于２时，每个子带中有两个迁移率边界。研究了扩展态、局域态以及迁移率边界随参数λ，ν，α的变化。 关键词：     

菌紫质同线偏振全息记录时再现光偏振方向对衍射效率的调制

当用相同偏振方向的物光和参考光在菌紫质薄膜上记录光栅时,再现光的偏振方向会影响其衍射效率.采用琼斯矩阵方法对此进行了理论分析,结果显示,再现光的偏振方向对衍射光的光强产生余弦调制;当再现光的偏振方向平行或垂直于记录光的偏振方向时,衍射光仍为线偏振光,其他情况下衍射光均变成椭圆偏振光.再现光偏振方向对衍射效率峰值的调制为正向余弦调制,对衍射效率稳定值的调制为反向余弦调制(与前者在相位上相差π).加入辅助紫光可抑制光栅的饱和,从而使得再现光偏振对衍射效率稳定值的调制由反向余弦调制变为正向余弦调制,并且提高了衍 关键词： 菌紫质 光致各向异性 衍射效率 琼斯矩阵     

Angular splitting of the Bragg diffraction order in an acoustooptical modulator due to a frequency-modulated acoustic wave

Effects of angular splitting of the Bragg diffraction order arising in light acoustooptical diffraction by a frequency-modulated acoustic wave are considered. These effects occur when the size of the light spot in the acoustooptical interaction zone exceeds the characteristic spatial period of the modulating function. The Bragg diffraction order is found to be split into several beams. The directions of the additional beams, their number, and intensities are determined by the modulation parameters. In particular, there occurs a situation where the diffracted field consists of three beams of equal intensity spaced at a distance approximately equal to the diffraction divergence of the incident beam and the diffraction total efficiency is of the order of 100%. Therein lies the difference between this diffraction regime and the case where several independent acoustic waves are generated in the interaction domain and the diffraction total efficiency is limited to the intermodulation arisen. The effect is used in design of modulators for systems of image plotting with the help of high-power lasers.     

Collinear diffraction of restricted light beams by nonmonochromatic sound

The collinear diffraction of Gaussian light beams by a two-frequency sound beam is investigated theoretically. A set of equations relating the amplitudes of transmitted and diffracted waves is derived in the case of third-order nonlinearity. The distributions of light intensities along an acousto-optical cell are calculated at different ratios between the radii of the light and sound beams. The transmission curves for detuned light waves and combination components of the diffracted waves are constructed at different ratios between the radii of the light and sound beams. The changes in the dynamic range of an acousto-optical device are calculated for different diffraction efficiencies.     

超冷原子中的拉曼增益光栅

为提高光栅的衍射效率,提出了基于主动拉曼效应的超冷原子光栅系统。理论研究表明：通过拉曼增益的空间周期性调节,可有效地将沿垂直光栅方向传播的弱探测光衍射到一级方向,同时零级衍射光将被放大。当系统中引进微波场的原子相干效应时,可以进一步提高光栅的一级衍射效率。在一定的条件下,拉曼增益光栅的一级衍射效率可高于电磁诱导相位光栅的一级衍射效率。该系统可作为高效光开关用于全光网络。     

超短脉冲激光光束被局域体全息光栅衍射的性质分析

利用二维耦合波理论,分析了超短脉冲激光光束被完全重叠型的局域体全息光栅衍射的时空变化性质,给出了衍射和透射脉冲激光光束沿光栅出射边界的强度时空分布。以LiNbO3晶体为例,数值研究了衍射光脉冲强度沿光栅出射边界的分布和脉冲波形的变化及光栅的总衍射效率受光栅二维尺寸、入射角度、光栅折射率调制度及入射脉冲的脉冲时域半峰全宽等条件的影响而变化的情况。与一维体全息光栅对超短脉冲激光光束衍射的性质,及此光栅对连续光衍射的性质作比较,给出了合理选择光栅参量及入射条件以在光栅出射边界上得到总衍射效率较大且分布较均匀的衍射光脉冲的方法。     

Airy beam laser

A method to design lasers that emit an arbitrary beam profile is studied. In these lasers, output-coupling is performed by a diffraction grating that imposes a phase and amplitude distribution onto the diffracted light. A solid-state laser emitting beams with a two-dimensional Airy intensity profile is demonstrated both theoretically and experimentally. In this case, the diffraction grating adds a transverse cubic phase to the diffracted light. An Airy beam is obtained by performing optical Fourier transform of the out-coupled light. The laser beam profile and power characteristics are shown to agree with theory.     

Far-field generation of localized light fields using absorbance modulation

In this Letter, we report the confinement of a uniform beam of light (lambda(1) = 400 nm) at the nodes of a standing wave (lambda(2) = 532 nm) via absorbance modulation. In the present implementation of absorbance modulation, a thin polymer film containing a photochromic azobenzene side chain is exposed to a standing wave at lambda(2) and a uniform beam at lambda(1), resulting in alternate regions of high and low absorbance. Light at lambda(1) is localized around the low-absorbance regions. Using photoresist exposures, we mapped out the localized light intensity distribution, which agrees well with our theoretical model. Since the width of this distribution is primarily determined by the ratio of the intensities at the two wavelengths, this technique opens up the possibility of localizing light fields below the diffraction limit using far-field optics.     

超短脉冲激光光束在一维反射型体全息光栅中的衍射

基于Kogelnik的耦合波理论,研究了在色散效应的影响下,超短脉冲激光光束在反射型体全息光栅中衍射的性质.研究给出了衍射光及透射光在频谱域及时间域的振幅及强度分布、光栅的光谱宽度及衍射效率随光栅参量及入射条件的变化.数值研究的结果表明,在光栅记录介质色散效应的影响下,衍射光束的光谱宽度减小,脉冲展宽,衍射效率降低.通过适当的选取光栅参量及入射条件,可以控制衍射和透射光束的频谱和时间强度分布,得到满意的衍射和透射光束的带宽和波形,从而可以将其应用于脉冲整形等技术中.     

部分相干平顶光束经光阑衍射的偏振特性

根据光束的相干-偏振矩阵和传输理论,对部分相干平顶光束经正多边形光阑衍射的偏振特性进行了系统的研究.给出了部分相干平顶光束偏振度传输公式,并将高斯-谢尔模型光束以及部分相干平顶光束在自由空间传输的偏振度作为特例统一于一般表达式中.研究表明：部分相干平顶光束经光阑衍射的偏振特性与光阑截断参数、光束的空间相干性、衍射角、传输距离、平顶光束的阶数有关. 关键词： 部分相干平顶光束 偏振特性 相干-偏振矩阵 正多边形光阑 光阑衍射     

Anisotropic gratings recorded from two circularly polarized coherent waves

A constant intensity, rectilinear light vibration, with spatially varying orientation, is obtained from superposition of two orthogonal circularly polarized waves propagating, in slightly different directions. Such an exposure on a photoanisotropic medium, prints a grating characterized only by spatial variations in the orientation of the induced optic axis. The diffraction properties of such a grating are investigated. It behaves as a uniformly transparent isotropic medium when illuminated by the same waves as during the recording process. Illumination by a circular wave, generates a transmitted and a single diffracted beam, while an incident elliptically polarized one would produce, apart from the central order, two diffracted beams with orthogonal circular polarizations.