Plasmon-induced transparency effect in hybrid terahertz metamaterials with active control and multi-dark modes

We numerically demonstrate a photo-excited plasmon-induced transparency (PIT) effect in hybrid terahertz (THz) metamaterials. The proposed metamaterials are regular arrays of hybrid unit cells composed of a metallic cut wire and four metallic split-ring resonators (SRRs) whose gaps are filled with photosensitive semiconductor gallium arsenide (GaAs) patches. We simulate the PIT effect controlled by external infrared light intensity to change the conductivity of GaAs. In the absence of photo excitation, the conductivity of GaAs is 0, thus the SRR gaps are disconnected, and the PIT effect is not observed since the dark resonator (supported by the hybrid SRRs) cannot be stimulated. When the conductivity of GaAs is increased via photo excitation, the conductivity of GaAs can increase rapidly from 0 S/m to 1×10⁶ S/m and GaAs can connect the metal aluminum SRR gaps, and the dark resonator is excited through coupling with the bright resonator (supported by the cut wire), which leads to the PIT effect. Therefore, the PIT effect can be dynamically tuned between the on and off states by controlling the intensity of the external infrared light. We also discuss couplings between one bright mode (CW) and several dark modes (SRRs) with different sizes. The interference analytically described by the coupled Lorentz oscillator model elucidates the coupling mechanism between one bright mode and two dark modes. The phenomenon can be considered the result of linear superposition of the coupling between the bright mode and each dark mode. The proposed metamaterials are promising for application in the fields of THz communications, optical storage, optical display, and imaging.     

一维和双层二维光子晶体太阳能电池背反射器

利用a-Si∶H和SiO2等介质,设计了一种由一维光子晶体和双层二维光子晶体组成的非晶硅薄膜太阳能电池背反射器.利用时域有限差分法对该背反射器在入射光波长范围为300~1 100nm波段的反射率和透射率进行仿真,计算不同结构参量下非晶硅太阳能电池短路电流密度并进行比较分析,最终得到了最佳背反射器结构.结果表明:设计的太阳能电池背反射器能够有效地延长入射光在太阳能电池吸收层的传播路径,有助于缓解太阳能电池吸收层厚度对电池吸收效率的影响,提高了电池吸收层对入射光的吸收效率.一维光子晶体和双层二维光子晶体结构的背反射器可以大幅度提高电池的光捕获能力,将非晶硅薄膜太阳能电池的短路电流密度提高到31.96mA/cm2,较常用的Ag/ZnO背反射器结构非晶硅薄膜太阳能电池提高了51.0%.     

Atom Lithography with a Chromium Atomic Beam

Direct write atom lithography is a new technique in which resonant light is used to pattern an atomic beam and the nanostructures are formed when the atoms deposit on the substrate. We design an experiment setup to fabricate chromium nanolines by depositing an atomic beam of ^52Cr through an off-resonant laser standing wave with the wavelength of 425.55 nm onto a silicon substrate. The resulting nanolines exhibit a period of 215±3 nm with height of I nm.     

沟道效应作用下中性原子在激光驻波场中的沉积特性研究

基于半经典理论,建立了中性原子与激光驻波场相互作用的模型,分析了中性原子在激光驻波场沟道效应作用下运动轨迹及沉积特性,探讨了球差、色差和原子束发散角对沉积条纹的影响. 得到了上述三种影响因素下纳米光栅的半高宽分别为0.532,12.16,96.70 nm. 仿真结果表明,随着原子束发散角度的增加,沉积条纹的对比度将会下降,当原子束发散角分别为0.1 mard时,其对比度为85.2：1,发散角为0.3 mrad时,条纹对比度为5.33：1,而当发散角增加至0.5 mrad以上时,沉积条纹将会出现分裂现象,导致条纹的恶化. 关键词： 激光驻波场 纳米光栅 沟道效应     

基片位置对激光会聚铬原子沉积的影响

为了研究基片位置对激光会聚铬原子沉积的影响,基于原子的粒子运动,采用数值计算对基片切割会聚激光场不同部位时高斯激光驻波场光学势阱、原子运动轨迹和沉积条纹进行了仿真。研究结果充分显示了基片位置对上述三方面的影响。虽然基片会对激光产生衍射,但是无论衍射存在与否,沉积条纹半峰全宽的最小值和中心峰值的最大值都出现在基片表面和激光中轴线重合的位置。此时,衍射将使条纹中心峰值降为非衍射时的0.96倍,同时,半峰全宽增加至非衍射时的1.03倍。另外,仿真结果显示,不管是否考虑衍射,垂直于激光中轴线方向(y方向)上沉积条纹的中心峰值随y值的增加呈现单调减小的趋势,而条纹半峰全宽随y值的增加呈现单调递增的趋势。     

空间光通信APT探测技术中位置敏感器件（PSD）的研究

鉴于空间光通信系统中分辨率在很大程度上影响着整个通信系统的性能，而PSD(position sensitive detector)作为APT(acquisition, pointing and tracking)子系统常用的探测器件，具有分辨率高，无盲区，响应速度较快的优点，分析了PSD的基本结构和定位原理，研究了使用PSD作为空间光通信APT子系统粗跟踪技术的位置分辨率，并指出了提高PSD分辨率的着手点。用实验方案对PSD的分辨率进行了具体的实验分析。通过对实验数据分析可知，PSD的平均位置分辨率达到12.6μm，该值与理论分辨率吻合得较好。这说明PSD作为APT子系统精跟踪探测器的可行性。     

基于偏振时域特性的海面耀光抑制方法

耀光是太阳光入射到海面上由海面镜面反射而成,其较高的辐射强度会造成传感器像元饱和,使得海面目标轮廓淹没在耀光中,对目标探测造成影响.基于耀光的偏振时域特性,提出一种耀光抑制方法.该方法利用实时偏振成像系统对有耀光的海面进行实时偏振测量,同时获取0°、45°、90°三个偏振方向的偏振视频图像信息;根据不同偏振方向视频对应...     

利用聚合脂质体的沉淀可逆性固定STI及其PL—STI对胰蛋白酶 …

通过双功能试剂戊二醛、二甘醇二酸酐和１,４－丁二醇双缩水甘油醚等将大豆胰蛋白栈抑制剂ＳＴＩ固定到由二十五－１０,１２－二块－１－醇磷脂乙醇胺形成的聚合脂质体上,同时探讨了其作亲和沉淀吸附剂对对胰蛋白酶的亲和作用。在ＰＬ沉淀过程中,胰蛋白酶有２０％～６０％从ＰＬ－ＳＴＩ 解离下来。ＰＬ－ＳＴＩ可作为酶的亲和沉淀吸附剂。