用光子晶体制作可见光超棱镜

据美国《Photonis Spectra》杂志报道，英国南安普敦大学与Mesophotonics有限公司的研究人员最近制备出了一种能够在可见光波长上工作的光子晶体超棱镜。这种光子晶体超棱镜的结构是通过用电子束平印术和干蚀刻法在位于N型硅上的氮化硅波导中蚀刻160nm直径气孔制成的。光子晶体呈186μm×500μm大小的长方形列阵状，它有600行气孔。     

二维光子晶体光波导透射特性的研究

用时域有限差分方法(FDTD)研究光波在光子晶体光波导中的传播规律,发现不同形状的波导能够导引不同频率的光波。光子晶体波导的带隙宽度和透射系数与该波导的结构和参数都有很大的关系,随着介质柱半径的变化,带隙呈现一定的变化规律,介质柱半径变小,该波导的带隙向高频方向移动,且带隙的宽度变宽;而介质柱半径变大时,光波的透射峰的峰值却变得比较大,损耗变小。研究结果为光子器件的设计提供了理论依据。     

多信道二维光子晶体滤波器

根据光波模在光子晶体线缺陷波导和环形谐振腔之间的耦合原理,在二维三角晶格光子晶体中设计了一款由线缺陷主波导、环形谐振腔、60°弯下载波导组成的多信道下载滤波器。利用平面波展开方法计算了完整光子晶体及线缺陷波导的能带结构;基于时域有限差分方法计算了各目标频率光信号在器件中的传输特性,分析了影响器件耦合效率的因素并对其进行了改进。分析表明:通过改变环形谐振腔内介质柱的半径可以调节光子晶体环形谐振腔的谐振频率,而改变线缺陷主波导与环形谐振腔之间耦合区域中介质柱的形状以及将直下载波导改换成60°弯下载波导可以提高线缺陷主波导、60°弯波导与环形谐振腔之间的耦合效率。计算结果显示:优化后的多信道二维光子晶体滤波器具备优良的选频功能,各目标频率光信号的透射率均达90%以上。与传统半导体介质材料器件相比,该器件体积较小,结构简单,易于大规模集成,很有应用前景。     

二维硅薄膜光子晶体波导的设计及制作

为了制作可用于通信波段的二维硅光子晶体波导,研究了光子晶体波导的设计方法及制作工艺。应用平面波展开法计算了两种空气孔型光子晶体结构的TE波禁带,经筛选采用了三角晶格空气孔结构。同样利用平面波展开法计算了引入缺陷后二维三角晶格空气孔型光子晶体波导结构的TE波禁带,经对比发现归一化频率为0.295 7的缺陷态最适宜用来制备光子晶体波导,并据此设计了用于1.55μm波长的二维三角晶格空气孔型光子晶体波导,其晶格周期为458nm,空气孔直径为339 nm。对设计的结构参数进行了容差计算,结果表明误差在-3.95~5.65 nm方能满足设计要求。最后使用聚焦离子束刻蚀工艺,制作了所设计的波导结构,并进行了测试。测试结果表明,样品实际晶格周期为463nm,空气孔直径为344 nm,比设计值大5 nm,在容差允许范围内,满足设计要求。     

二维光子晶体波导传输特性的研究

为了研究二维光子晶体波导的传输特性,应用平面波展开法计算得到在0．216～0．35229,0．432-0．48386,0．76886-0．79716Hz波段的光波能在波导中很好的传输。并且分析了当圆柱半径从0．1a～0．5a发生改变时的带隙规律,从而为光子晶体波导器件的开发提供了理论依据。     

基于正四边形晶格的微结构光子晶体光纤的特性分析

设计了基于正四边形晶格空气孔排列的光子晶体光纤,并在此基础上,通过在纤芯附近引入不同的微结构空气孔,运用全矢量有限元差分法,对不同微结构的光子晶体光纤的模式有效折射率、限制损耗、模场有效面积、非线性系数、波导色散系数等特性参数进行了仿真与分析。结果表明:引入不同的微结构,可以减小有效模场面积和增大非线性系数;引入正四边形微结构空气孔时,其限制损耗整体变化幅度较小;引入正八边形微结构空气孔时,其对应的波导色散系数在中波段变化比较平坦,且在波长为1 550nm处波导色散系数接近于零;引入正十二边形微结构空气孔时,其波导色散系数均为负值且变化幅度不大,可以应用于光纤的色散补偿。根据对引入不同微结构的光子晶体光纤的特性研究,为进一步研究光子晶体光纤提供一定的参考。     

光子晶体改善中红外辐射的发生

在硅片中设计的一种光子晶体使得用户能够有控制地产生中红外辐射，由美国Ion光学公司研制的这种发射器正准备投入环境监测应用。据有关专家解释说，中红外辐射一般由热灯丝、发光二极管或者量子级联激光器发生。该公司的研究人员在一块硅片上先覆盖一层玻璃，然后再覆盖一层黄金或者一层铂     

新型光子晶体显示技术

加拿大科学家开始利用光子晶体技术（P—Ink）制造一种新型的柔性电子纸显示器。这种光子晶体显示器不同于其他此类装置，首次实现了像素单独可调，能够将每个像素调节成任何颜色，从而提供更鲜艳的颜色和更高的清晰度。     

基于拓扑单向波导的电磁诱导透明效应研究

为了研究电磁诱导透明效应在拓扑单向波导中的表现，设计了一种基于磁性光子晶体的耦合谐振腔波导。通过对谐振腔位置的调控实现了具有单向性质的电磁诱导透明效应，并利用有限时域差分仿真证明了电磁诱导透明效应在单向拓扑波导中的相关特性。该研究可为拓扑波导中实现光延迟、光开关等提供参考。     

具有缺陷的一维光子晶体空间滤波器

具有缺陷的一维光子晶体结构中,群速度延迟在缺陷模处会发生突变,从而共振隧穿的光波会发生大的测向位移。将具有多个缺陷的一维光子晶体作为色散元件,设计了能够将两通道和三通道滤光片在斜入射条件下进行波长空间分离的空间滤波器。该空间滤波器具有制备简单、能够同时进行多路空间滤波的特点。     

A quasioptical directional coupler on diffraction-coupled transmission lines

A circuit and principle of operation of directional couplers based on diffraction-coupled transmission lines, the emitting apertures of which are formed from periodic structures and dielectric waveguides, are described. The experimental studies of the coupler prototype in a 30- to 37-GHz band have shown that the coupling on spatial waves allows one to obtain transient attenuation values in a 3- to 20-dB interval at a ～30-dB directivity, this being roughly in conformity with similar characteristics of a coupler on dielectric waveguides. The main advantage of the described directional coupler is that it is possible to correct its characteristics over wide ranges by changing the distance between the emitting apertures.     

Adjustable Directional Couplers

The characteristics of directional couplers with coupling factors of 3.0 and 12.6 dB at 1.3 GHz are calculated. The devices are based on 165.1 × 82.5 mm² rectangular waveguides coupled through their common narrow walls. In both devices, the coupling factor can be varied within ±1 dB relative to its nominal value (at a directivity of no less than 25 dB). The adjustment is accomplished by shifting movable shorts in auxiliary 276.0 × 82.5-mm² waveguides connected to the coupler narrow walls from two sides and placed opposite to the coupling apertures. Simulation results obtained on reduced-scale devices confirm the numerical data.     

硅微光机械加速度地震检波器中M-Z光波导干涉仪结构设计

提出了一种新型的硅基M-Z干涉型光电集成加速度地震检波器。对硅基微光电机械加速度地震检波器的M-Z光波导干涉仪系统进行了系统研究和优化设计,采用K9玻璃作为基底层和包层材料,Bak7玻璃作为波导层材料,波导的宽度为4 μm,厚度为0.4 μm。M-Z光波导干涉仪的Y分支设计中采用上升反正弦S型弯曲,为适用于该干涉仪的信号臂和参考臂大跨距的特殊结构,应用波导转向镜实现了大角度光路转折,反射转向镜的内介质采用镀制金属铝膜得以实现,并利用BPM进行了仿真。为了防止TE模偏振光的偏振态经铝膜全反射后发生变化,加了4个长度为1 mm的TE模偏振器以保持其偏振态。实验结果与理论相符。     

基于SH模态导波杆的电站高温结构壁厚测量方法

提出了一种基于SH模态导波杆的电站高温结构壁厚测量方法,该方法使用导波杆将压电传感器与高温被测结构隔开。通过研究发现非频散SH模态导波能通过矩形横截面导波杆将导波信号由传感器导入到高温被测结构中。实验验证了通过特定夹具以干耦合方式将导波杆固定在被测结构表面可以获得较好的信号。使用2MHz中心频率下的汉宁窗调制正弦波信号实现了对处于不同温度被测结构壁厚的监测,室温（25℃）时,壁厚测量值与实际厚度相差0.016mm,高温被测结构实验信号也非常好,波速测量值与拟合曲线所得速度值误差范围为0.1%～2.5%。     

Application of microscopical techniques in the study of autolysosome dynamics in PC12 neurites

Autophagy is a principal degradation pathway for the turnover of intracellular proteins or cytoplasmic organelles in response to starvation. During autophagic activation, autophagosomes fuse with lysosomes to form autolysosomes where incorporated materials are degraded. However, the dynamics of autolysosomes in neurites of live cells was still poorly known. In this study, various subsets of microscope were applied to analyse the autophagy induction and highly dynamic transport of autolysosomes in rat PC12 neurites. Beading formation was found in degenerating PC12 neurites under phase contrast light microscope after serum deprivation. The monomeric red fluorescence protein‐green fluorescence protein‐light chain 3–labelled autolysosomes accumulated throughout PC12 neurites after 18 h of serum deprivation as revealed by fluorescence microscope analysis. The single‐membrane autolysosomes were also visualized in PC12 cells under transmission electron microscope. Moreover, fluorescence recovery after photobleaching experiment, which was conducted by confocal laser scanning microscope, demonstrated that autolysosomes were motile vesicles and moved along PC12 neurites during starvation. The directional transport of monomeric red fluorescence protein ‐labelled autolysosomes in neurites was further monitored by a motorized video microscope. Both anterograde and retrograde transport of autolysosomes were observed. In addition, the autolysosomes were precisely mapped by using 2D Gaussian fitting and then their highly dynamic movement was robustly tracked by using multidimensional assignment. Collectively, by using different microscopical techniques, our results confirmed the dynamic transport of autolysosomes in starved PC12 neurites and may provide valuable insight into understanding the biophysical characteristics of autolysosomes in neurites under physiological and pathological conditions.     

一类基于轨迹预测的驾驶员方向控制模型

驾驶员方向控制模型在人-车-路闭环系统仿真、驾驶员辅助系统开发和智能汽车控制中具有重要作用。在假设驾驶员具有汽车轨迹预测能力的基础上,提出一类基于轨迹预测的驾驶员方向控制模型。分别假定汽车在将来一段时间内保持恒定的横摆角速度或横摆角加速度,并结合汽车状态参数预测汽车的行驶轨迹,采用期望式、增量式以及期望式与增量式集成的转角决策方法建立5种不同的驾驶员模型。在ve DYNA/Simulink联合仿真平台上对各驾驶员模型进行仿真试验,结果表明,增量式驾驶员模型表现出良好的路径跟踪精度和很强的鲁棒性,期望式模型的转向操纵更加平滑,而集成式模型则具备综合优势。在ve DYNA/Labview硬件在环实时试验台架上对所提出的驾驶员模型进行模拟试验,所得结论与仿真基本一致。     

Robotic automatic assembly system for random operating condition

A vision guided tabletop robotic assembly system is constructed for the random environment automatic assembly purpose. The distributed control structure is designed for this assembly system. A PC is specified as the central control unit for machine vision operation and the harmonization of At89c51 distributed control unit for each axis. The machine vision is introduced to search the locations and measure the size of the assembly parts in the robotic workspace. Then, the central controller commands the robot to pick the part sequentially based on the specified program to complete the automatic assembly process. The model-free fuzzy sliding mode control scheme is embedded in each joint micro controller for simplifying the model based control problem. The central control unit PC communicates with each joint controller by network communication. This assembly system is implemented on a 3 DOF SCARA robot. The experimental results show that the robotic motion control performance is good enough for assembling work; the vision pattern classification and assembly motion paths planning and monitoring are exactly executed by the central control unit. The goal of this robotic random assembly operation is achieved with the appropriate integration of robotic motion control, machine vision, sensor and assembly force detecting techniques.     

Investigation of the temperature coefficient of the effective refractive index of optical sol-gel waveguides using a Peltier module

A method for studying the temperature dependence of the effective refractive index of optical waveguides was proposed and tested. The samples were heated using a Peltier thermo-optic module. This technique is simple and easy and improves the measurement accuracy and capabilities of temperature studies of optical waveguides and the materials from which they are made. Obtained dependences can be used to determine the thermo-optic coefficient of film materials. The method was tested on optical waveguides using SiO₂-TiO₂ films produced by sol-gel technology.     

麻花钻CAD/CAM系统

介绍了在微机上开发的麻花钻CAD/CAM系统的总体结构及各功能模块 ,探讨了产生式原理在工艺设计中的应用。     

质子交换Z切LiNbO3光波导电光效应的研究

电光效应是LiNbO3光波导的重要特性。但质子交换对LiNbO3光波导的电光系数γ33有较大的损失,当经过一定时间的退火处时后,其值得到一定程度的恢复。采用相位检测法,测量电光系数γ33值。分别对质子交换和退火后的LiNbO3光波导进行测试。并用对测试结果进行了分析,得出了合理的结论。