单轴晶体和各向同性介质交界面上e光光线的折射

根据光在各向异性介质中遵从的Ｆｅｒｍａｔ 原理,较系统地讨论了单轴晶体和各向同性介质交界面上的ｅ 光（ 非常光） 光线的折射,得到了光轴在任意取向情况下的折射基本公式。同时给出一般情况下确定ｅ 光线折射角的具体解。在此基础上对几种特殊的光轴取向给予了较详细的讨论。最后讨论了ｅ 光线的折射公式与ｅ 光波法线的折射定律的等价性,从而说明Ｆｅｒｍａｔ 原理与光的电磁波理论存在内在的一致性。     

电流变液中的双折射现象观察

本文研究了电流变液(ER流体)可调节的双折射现象,激光束垂直于电场方向,利用He-Ne激光器对SiO₂、季戊四醇和硅油组成的ER流体进行测量.发现当一对偏振片互相正交,不加电场时,没有光线射出;当施加电场时,就有光线射出,透射光强度随电场增大.对于相同材料的ER流体,低浓度的ER流体双折射现象更加明显,电流变液双折射现象起因于颗粒在电场作用下排列成链状或柱状结构.     

基于三角谐振环的新型六边形谐振环金属线复合周期结构左手材料性质研究

通过实验及仿真研究了三角谐振环组合新型六边形谐振环金属线复合周期结构左手材料.仿真研究了以金属铜三角开口谐振环（SRRs）为基本单元的周期结构负磁导率材料,与闭口环（CSRRs）结果对比发现三角开口谐振环能产生很好的谐振效果即能产生负磁导率,并且多层单元仿真发现多个谐振环耦合能提高谐振频率并加宽谐振频段;设计、制作并实验和仿真研究了三角开口环为基本单元的六边形谐振环金属线复合周期结构左手材料,仿真结果在98GHz附近出现良好负折射效应,实验验证在93—108 GHz出现良好负折射效应,与仿真结果具有良好的一致性.该研究对新型周期结构左手材料的研究、设计和研制具有重要的科学意义和应用前景. 关键词： 左手材料 三角环组成的六边形谐振环 负折射     

1维光子晶体缺陷模

 利用光学传输矩阵理论对掺杂1维光子晶体的缺陷模进行了研究。计算和分析了缺陷层折射率、缺陷层厚度与缺陷峰的关系。得出结论：随着缺陷层厚度的增大,缺陷峰波长呈线性增加,但是当缺陷层厚度增加到一定值时,缺陷峰的个数也将不断增加;缺陷层折射率也与缺陷峰波长有线性正比关系。从而提出了一种在微波领域测量介质折射率和介电常数的有效方法。     

KDP晶体折射率非均匀性检测系统

基于正交偏振干涉法,建立了KDP晶体折射率非均匀性的检测系统,并可实现晶体相位失谐角的间接检测.波前检测系统实现了测试光偏振态的精密控制与切换,采用波长调谐相移的方法去除了测试过程中参考面倾斜引入的误差,优化了抗振动相移算法,提高了波前测试的测量准确度及重复性.通过折射率非均匀性分析算法的设计,解决了晶体厚度变化引入的误差等.小口径晶体元件的测试结果表明系统的折射率非均匀性检测准确度(均方根值)优于10~(-6).     

决定介质折射率因素的经典计算

就介质折射率的物理意义首先从理论上作了说明,然后从经典概念出发对介质折射率的表达式作了推导,指出了决定介质折射率的因素,即组成介质的原子结构、原子种类、每一个原子周围电子分布的情况及辐射的频率。通过理论计算和实验数值的对比表明,所推导出的结论及相关的计算方式是正确的,对介质折射率的研究和在特殊领域对折射率有一定要求的材料的制备具有一定的指导意义。     

Using metamaterial yokes in NMR measurements

Swiss rolls are one instance of metamaterials, and can be described as an effective medium with a complex, anisotropic magnetic permeability. It has been shown that bundles of Swiss rolls can guide the magnetic flux in magnetic resonance measurements and increase the coupling between the nuclear spins and the receiver coil. Here, we investigate, with a numerical model, whether Swiss rolls can boost the detected signal in a NMR experiment, where the rolls could provide a low-reluctance return path for the magnetic flux when shaped in a yoke encircling the sample. The system consisting of the nuclear spin, the rolls and the receiver coil is analyzed with the method of finite differences in time domain (FDTD). The results show that small gains in the received signal are possible, but only if the losses (resistive and dielectric) in the rolls are reduced by over one order of magnitude from their present value in state-of-the-art materials. This situation arises because of the energy dissipation in the rolls and the mode splitting caused by the coupling between the rolls and the resonant coil.     

Development of Methods to Determine the Infrared-Optical Properties of Polymer Films

Summary: In this paper, two methods for the determination of infrared optical properties of thick polymer films, based on FTIR spectroscopy, were implemented and used. Complex index of refraction data were generated for various ethylene copolymer films. Transmittance and reflectance spectra were measured in the mid infrared range using a gold-coated 100 mm-diameter integrating sphere. For the investigated films n and k values ranging from 1.3 to 1.6 and from 10⁻⁴ to 0.25 were determined, respectively. Regarding n, a good agreement was obtained for both methods, the transmittance/reflectance procedure (T/R method) used for transparent and semitransparent regions, and Single Substractive Kramers-Kronig (SSKK) algorithm applied for non-transparent regions. The highest k values were determined for the CH₂ stretching vibration. The k values are dependent on comonomer content and film thickness. The combination of both methods allows for an accurate determination of n and k in the entire IR region relevant for solar application.     

大口径KDP晶体折射率非均匀性检测

KDP晶体的折射率不均匀性将导致光束的空间分布存在不同程度的相位失配,从而使得三倍频系统的转换效率下降。为了得到KDP晶体折射率非均匀性的高精度检测结果,基于正交偏振干涉法,采用ZYGO MST大口径干涉仪,测量得到了大口径KDP晶体折射率非均匀性分布,其测量精度达到10-7,并通过实验研究了晶体面形对测量结果的影响。对晶体e光折射率非均匀性的高精度检测,为大口径晶体材料生长工艺、加工工艺等改进和提高提供了定量的检测依据。     

Acoustic metasurface for refracted wave manipulation

Here we present a design of a transmitted acoustic metasurface based on a single row of Helmholtz resonators with varying geometric parameters. The proposed metasurface can not only steer an acoustic beam as expected from the generalized Snell's law of refraction, but also exhibits various interesting properties and potential applications such as insulation of two quasi-intersecting transmitted sound waves, ultrasonic Bessel beam generator, frequency broadening effect of anomalous refraction and focusing.