Wet-etching fabrication of multilayer GaAlAs/GaAs microtips for scanning near-field optical microscopy

We propose to fabricate GaAlAs/GaAs multilayer microtips for scanning near-field optical microscopy (SNOM) using anisotropic etching. The etching was performed in a solution of H₃PO₄:H₂O₂:H₂O operating at a temperature of 10 °C. We obtained pyramid-shaped microtips with four etched facets and with a radius of curvature at the apex that was lower than 50 nm.     

High-sensitivity piezoelectric tube sensor for shear-force detection in scanning near-field optical microscopy

An easy-to-implement non-optical shear-force detection setup for tip–sample distance regulation in scanning near-field optical microscopy is demonstrated. The detection method is based on attaching the near-field probe to a piezoelectric tube resulting in excellent mechanical contact between tip and detector. The main advantages of the method are good signal-to-background contrast and thus potential for high sensitivity. The method is demonstrated by obtaining approach curves of silicon surfaces. The suitability for optical experiments is further shown by measuring the near-field intensity distribution of the emission of a semiconductor laser.     

Misalignment tolerance analysis and fabrication for highly efficient parallel optical-electrical convertor module

A compact, highly efficient, and passively assembled parallel optical-electrical convertor module (POECM) for active optical cable application is proposed. This paper presents our POECM structure, optical design simulation results, fabrication process, and data transmission test results, in sequence. The POECM has a compact size of \(18.5\hbox {mm} \times 10\hbox {mm} \times 2.8\hbox {mm}\) . We confirm a data rate of total throughput at 21.6 Gbps ( \(5.4\hbox {Gbps} \times 4\) channels) with a bit error rate of less than \(10^{-12}\) .     

Optimal design and fabrication of SMS fiber temperature sensor for liquid

Single-mode/multi-mode/single-mode (SMS) fiber sensors are optimally designed and used as high sensitivity temperature sensors in special temperature range. It is shown that the width of multi-mode fiber is a key factor influencing the performance of as-fabricated temperature sensors, which can be effectively controlled in the fabrication process by monitoring the output power of SMS fiber during wet acid etching process. As-fabricated temperature sensors show promising potential applications for precisely monitoring chemical reaction temperature in chemistry and biomedicine fields.     

Resonantly excited ZnO nanowires for fabrication of high sensitivity gas sensor

A novel approach for gas sensing based on mechanical resonance of ZnO nanowires is reported. For this purpose, ZnO nanowires were grown between comb-like electrodes using a novel oxygen plasma treatment approach. Then gas measurements were carried out at different agitating frequency. Results show an improvement in gas sensitivity of resonantly excited ZnO nanowires. Our results open up a promising approach to fabricate high sensitivity gas sensor. Also we have introduced an alternative frequency modulation gas detection method here.     

用于位移传感器的全息平面变间距光栅设计与制作研究

简述了全息变间距光栅的几何理论.利用遗传算法对记录光路进行了优化计算，提出在目标函数中考虑记录参数误差的影响，推导了目标函数的积分形式，提高了计算效率.针对用于位移传感器的平面变间距光栅，分别计算了球面波干涉及球面波与非球面波干涉情况下的全息记录参数，给出了线密度误差曲线.制作出全息平面变间距光栅，并成功应用于位移传感器中. 关键词： 全息光栅 变间距光栅 遗传算法     

Optical communication fiber waveguide fabrication: A review

Abstract

The current state of the art in optical communication fiber waveguide fabrication is reviewed. Details of the two main technologies—multi-component glasses and high-silica glasses—are described, followed by brief details of other fiber fabrication techniques. The relative advantages and disadvantages of the different fiber fabrication techniques are discussed in the summary.     

Optical communication fiber waveguide fabrication: A review

The current state of the art in optical communication fiber waveguide fabrication is reviewed. Details of the two main technologies—multi-component glasses and high-silica glasses—are described, followed by brief details of other fiber fabrication techniques. The relative advantages and disadvantages of the different fiber fabrication techniques are discussed in the summary.     

Polymer waveguide module for visible wavelength division multiplexing plastic optical fiber communication

We report a polymer waveguide module that provides bidirectional communication over a single plastic optical fiber (POF) with dual visible wavelength LEDs. The module is constructed using light-induced self-written waveguides, which enables a three-dimensional optical circuit for visible wavelength division multiplexing to be fabricated by an extremely simple process. We demonstrated 250 Mbits/s communication using a pair of these modules that each contained one green (lambda = 495 nm) and one red (lambda = 650 nm) LEDs by measuring the bit error rates. The results indicate that the system could transmit over more than 20 m of POF in full duplex mode.     

Electrooptic prepulse suppression for fusion laser systems

We report on an effective electrooptic prepulse suppression technique with particular applicability to fusion laser systems. Three optically timed Pockels cells in series have a contrast of 10⁹. They are driven by a laser activated Si high voltage switch of 5 ps jitter and < 100 ps rise time. The resulting overall rise time of the three Pockels cells is 600 ps over the first 6 decades and 1.5 to 2 ns over 9 decades.     

基于水声传感器网络的多路径协同多跳通信研究

针对水声网络高误码、大时延的特点,借鉴提出了一种多路径协同多跳通信协议,该协议通过多路径、多节点的协同多跳中继通信以及冗余判决,来完成网络中端对端的远程数据传输。通过数值仿真试验分析表明:与普通的点对点直接通信和单路径多跳中继通信方式相比,此协议具有低误码、高能效的特点(距离与能量相同时,误码率低一至两数量级;限定误码率时,每比特能耗降低一个数量级),能够减少数据重发几率,提高网络的通信效率和工作寿命,特别适于水声传感器网络应用。     

Electrooptic effect for cold neutrons in photorefractive materials

First experimental evidence for the existence of an electrooptic effect for cold neutrons in ⁷LiNbO₃ is reported and discussed. The effect is based on the fact that in certain photorefractive crystals a light-induced space-charge field can be generated which causes a modulation of the density via the inverse piezoelectric effect. From such density structures, induced by the internal electric field, cold neutrons can be diffracted. Received: 13 November 1998 / Revised version: 21 December 1998 / Published online: 12 April 1999     

Application of dielectrophoresis to fabrication of carbon nanohorn gas sensor

This paper describes an electrokinetic fabrication method for a gas sensor composed of single-wall carbon nanohorns (SWCNHs) using dielectrophoresis (DEP). The authors have previously demonstrated that DEP manipulation of carbon nanotubes (CNTs) can be applied to the fabrication of a CNT gas sensor. In the present study, we further explored the possibility of electrokinetic manipulation of SWCNHs. The latter have different structures and properties compared to CNTs. The SWCNHs were synthesized using the ‘arc in water with gas injection’ method. The SWCNH aggregates were dispersed in ethanol and trapped in an interdigitated microelectrode gap under the action of positive DEP. After the DEP process, the ethanol was evaporated and the microelectrode retaining the SWCNHs was exposed to nitrogen dioxide (NO₂) or ammonia (NH₃) gas while the electrode impedance was monitored. It was found that conductance of the DEP-fabricated SWCNH sensor increased or decreased upon exposure to ppm-levels of NO₂ or NH₃, respectively. These results were similar to those previously obtained for CNT gas sensors and suggest that the SWCNH aggregate behaves as a p-type semiconductor. The comparison reveals that intrinsic NO₂ sensitivity of the SWCNHs is lower than that of single-wall CNTs (SWCNTs) but comparable with the intrinsic sensitivity of multiple-wall CNTs (MWCNTs).     

A study of a liquid-filled lens module with a flexible sensor for aberration correction

This study introduces the concept of a liquid-filled lens module; the module is composed of a flexible lens membrane, a flexible sensor membrane that is constructed by attaching sensor chips onto a flexible substrate and transparent liquid that fills the space between the flexible lens membrane and the sensor membrane. The image quality of the liquid-filled lens module is comparable to that of a solid lens module with a flat-type image sensor. However, the liquid-filled lens module has the advantages of requiring fewer parts, having better optical aberration compensation, a wider image range. This study identifies the optimized conditions for the sensor membrane to fulfill the Petzval surface of the optical module and the compensation mechanism of the flexible lens and the sensor membranes. The simulation results show that the distortion aberration, the field of curvature and the Modulation Transfer Function are good.     

Cloaked near-field scanning optical microscope tip for noninvasive near-field imaging

Near-field imaging is a well-established technique in biomedical measurements, since closer to the detail of interest it is possible to resolve subwavelength details otherwise unresolved by regular lenses. A near-field scanning optical microscope (NSOM) tip may indeed overcome the resolution limits of far-field optics, but its proximity inherently perturbs the measurement. Here, we apply the recent concept of a "cloaked sensor" to an NSOM device in collection mode, showing theoretically how a proper plasmonic cover applied to an NSOM tip may drastically improve its overall measurement capabilities.     

片上制备横向结构ZnO纳米线阵列紫外探测器件

将纳米技术与传统的微电子工艺相结合, 片上制备了横向结构氧化锌(ZnO)纳米线阵列紫外探测器件, 纳米线由水热法直接自组织横向生长于叉指电极之间, 再除去斜向的多余纳米线, 其余工艺步骤与传统工艺相同. 分别尝试了铬(Cr)和金(Au)两种金属电极的器件结构: 由于Cr电极对其上纵向生长的纳米线有抑制作用, 导致横向生长纳米线长度可到达对侧电极, 光电响应方式为受表面氧离子吸附控制的光电导效应, 光电流大但增益低, 响应速度慢, 经二次电极加固, 纳米线根部与电极金属直接形成肖特基接触, 光电响应方式变为光伏效应, 增益和速度得到了极大改善; 由于Au电极对其上纵向生长的纳米线有催化作用, 导致溶质资源的竞争, 相同时间内横向生长的纳米线不能到达对侧, 而是交叉桥接, 但却形成了紫外光诱导的纳米线间势垒结高度调控机理, 得到的器件特性为最优, 在波长为365 nm的20 mW/cm²紫外光照下, 1 V电压时暗电流为10^-9 A, 光增益可达8×10⁵, 响应时间和恢复时间分别为1.1 s和1.3 s.     

Electrooptic study of antiferroelectric mixtures for display application

The aim of this paper is to study the influence of electric field on alignment of para-, ferro- and antiferroelectric phases in the vicinity of SmA^* — SmC^* or SmC^* — SmC _A ^* phase transitions as to obtain mono-domain cells. Four mixtures studied (W-193B, W-193B-1, W-201, W-204D) show the SmC _A ^* phase in a wide room temperature range. Measurements of the spontaneous polarization versus temperature by using reversal current method give an answer to the question, what kind of the transitions take place between para-, ferro- or antiferroelectric phases using the Landau mean field theory. Optimal electrooptic parameters for different compositions of the mixtures such as tilt angle, spontaneous polarization and saturation voltage have been measured to compare parameters of the mixtures studied.     

Mach-Zehnder电光波导调制器啁啾的研究

在光纤通信系统中,调制器的啁啾参数是衡量调制器性能的重要参数之一.为了深入研究铌酸锂M-Z结构外调制的机理,导出了Mach-Zehnder结构外调制方式调制器的啁啾参数表达式,研究表明该结构调制器频率啁啾不为零,而且调制器的直流偏置漂移对啁啾的影响很小.详细讨论了影响啁啾参数的因素,分析了直流消光比、外加信号以及直流偏置漂移对器件啁啾参数的影响.分析结果表明,利用负啁啾可以改善系统的色散特性.     

无线通信系统电磁脉冲传导防护组件设计与有效性试验验证

为提高甚高频无线通信系统的抗高空电磁脉冲能力,基于易损性分析结果,确定了瞬态泄流和稳态滤波联合防护的设计思路以及设计指标,并研制了防护样件。使用20 ns/500 ns传导注入波形开展防护组件脉冲注入试验,比系统原始防护器残余电流峰值减小60%,启动时间缩短75%,作用时间缩短80%,注入波形低频能量限制（20 MHz以下）提高1个量级;以某甚高频无线通信系统为被试品,开展了防护组件加固验证试验,防护组件残余电流控制在10 A水平以下,被试系统功能和性能指标正常,验证了防护组件设计的有效性。