液晶光学相位共轭镜的研制

本文研制了一种由向列型液晶和非晶硅光导层组成的新型光学相位共轭镜。概述了该器件产生相位共扼波的原理,通过实验测试了器件的性能。测试表明,该器件有灵敏度高(20μW/cm²)、响应速度快(5ms)、光谱响应范围宽、结构紧凑等特点。由于响应快,器件能在没有防振装置的实验桌上输出相位共轭波,这对相位共轭的推广应用有重要意义。为了提高共轭光强,实验中还使用了一种脉冲增强技术,它将共轭光的功率提高了一个量级以上。     

基于北斗的高精度时空服务设备的研制

为提供基于北斗的高精度授时/定位服务,设计了一种小型化、多通路的时空服务设备。该设备采用高性能多核DSP和FPGA作为主处理器,实时采集和处理北斗卫星数据,从而为终端提供精准的北斗时间/位置,以及北斗短报文通信功能。同时,利用设备内部高性能恒温晶振产生与北斗时间高度同步的时间基准,为卫星失锁时提供可靠的守时数据。此外,为满足不同设备使用需求,主处理器进行了多种类型接口的扩展。经多台设备试验证明,该设备提供的授时、守时以及位置等各项信息精度指标均满足设计要求。     

A double pass rapid scanning Fourier transform spectrometer for plasma diagnostics

The construction and the performance of a double pass rapid scanning Fourier transform spectrometer are described. The instrument covers a frequency range below 900 GHz. It has a maximum spectral resolution of 6.6 GHz and a maximum time resolution of 10 msec. The spectrometer has been applied to JIPP T-II device at Institute of Plasma Physics in Nagoya University. Electron cyclotron emission from the device has been measured and the electron temperature of the plasma has been obtained. The results are shown.     

An investigation into the simultaneous use of a resonator as an energy harvester and a vibration absorber

A mass–spring–damper system is at the core of both a vibration absorber and a harvester of energy from ambient vibrations. If such a device is attached to a structure that has a high impedance, then it will have very little effect on the vibrations of the structure, but it can be used to convert mechanical vibrations into electrical energy (act as an energy harvester). However, if the same device is attached to a structure that has a relatively low impedance, then the device may attenuate the vibrations as it may act as both a vibration absorber and an energy harvester simultaneously. In this paper such a device is discussed. Two situations are considered; the first is when the structure is excited with broadband random excitation and the second is when the structure is excited by a single frequency. The optimum parameters of the device for both energy harvesting and vibration attenuation are discussed for these two cases. For random excitation it is found that if the device is optimized for vibration suppression, then this is also adequate for maximizing the energy absorbed (harvested), and thus a single device can effectively suppress vibration and harvest energy at the same time. For single frequency excitation this is found not to be the case. To maximize the energy harvested, the natural frequency of the system (host structure and absorber) has to coincide with the forcing frequency, but to minimize vibration of the host structure, the natural frequency of the absorber has to coincide with the forcing frequency. In this case, therefore, a single resonator cannot effectively suppress vibration and harvest energy at the same time.     

具有纵向漏极场板的低导通电阻绝缘体上硅横向双扩散金属氧化物半导体器件新结构

为降低绝缘体上硅(SOI)横向双扩散金属氧化物半导体(LDMOS)器件的导通电阻,同时提高器件击穿电压,提出了一种具有纵向漏极场板的低导通电阻槽栅槽漏SOI-LDMOS器件新结构.该结构特征为采用了槽栅槽漏结构,在纵向上扩展了电流传导区域,在横向上缩短了电流传导路径,降低了器件导通电阻;漏端采用了纵向漏极场板,该场板对漏端下方的电场进行了调制,从而减弱了漏极末端的高电场,提高了器件的击穿电压.利用二维数值仿真软件MEDICI对新结构与具有相同器件尺寸的传统SOI结构、槽栅SOI结构、槽栅槽漏SOI结构进行了比较.结果表明:在保证各自最高优值的条件下,与这三种结构相比,新结构的比导通电阻分别降低了53%,23%和提高了87%,击穿电压则分别提高了4%、降低了9%、提高了45%.比较四种结构的优值,具有纵向漏极场板的槽栅槽漏SOI结构优值最高,这表明在四种结构中新结构保持了较低导通电阻,同时又具有较高的击穿电压.     

适用于深亚微米NMOSFET ESD效应的非本地传输模型

分析了深亚微米NMOSFET在ESD应力下的非本地传输特性，分析说明了速度过冲效应可以增大漏端电流，改变器件特性. NMOSFET能量弛豫时间与器件中该点的电场、载流子速度和载流子能量密切相关，从而不能再近似为一个常数.利用蒙特卡罗仿真方法得到电子能量弛豫时间和电子高场迁移率与电子能量的关系表达式，并使用上述模型进行了ESD器件仿真，与实验结果的对比显示，使用该能量弛豫时间模型和高场迁移率模型可以得到准确的器件I-V曲线. 关键词： 静电放电 速度过冲 能量弛豫时间     

Z箍缩诊断系统的触发和抗干扰技术

通过对时间关联信号的筛选、转换和延时等方法建立了用于8 MA脉冲功率装置上Z箍缩实验中诊断设备的触发网络,其输出触发信号与被测X射线之间的时间抖动小于2 ns,满足了纳秒级的诊断时间同步要求。采用屏蔽、接地等有效措施基本消除了放电产生的强电磁环境以及其它杂散信号对触发线缆和诊断设备的干扰,保证了诊断设备的正常工作和实验数据的质量。     

Performance analysis of indium phosphide channel based sub-10 nm double gate spin field effect transistor

In this paper, a novel double gate Spin-Field Effect Transistor (DG spin-FET) with indium phosphide (InP) as channel material is evaluated. The proposed spin-FET device is well suited for CMOS technology, as both n and p-type devices can be formed by using parallel and anti-parallel combinations of spin-FET respectively. The proposed device feature size is in sub 10 nm range and therefore is compatible with state of the art integrated circuit technology. The leakage currents have been reduced by employing high-k dielectric (HfO₂). A comparative analysis of the proposed device with the devices reported in the literature confirm that the proposed device has improved on-off ratio and ON current. Besides the device has low transit time and less parasitic capacitances required for high frequency and low power applications respectively.     

The simulation of temperature dependence of responsivity and response time for 6H-SiC UV photodetector

In this paper the temperature dependence of responsivity and response time for 6H-SiC ultraviolet (UV) photodetector is simulated based on numerical model in the range from 300K to 900K. The simulation results show that the responsivity and the response time of device are less sensitive to temperature and this kind of UV photodetector has excellent temperature stability. Also the effects of device structure and bias voltage on the responsivity and the response time are presented. The thicker the drift region is, the higher the responsivity and the longer the response time are. So the thickness of drift region has to be carefully designed to make trade-off between responsivity and response time.     

基于分时原理的多相流体比例分配方法

提出了从“时间”上对多相流进行分配的新思路,分析了分时分配的基本原理,并设计了具体的实现方式。在空气-水实验回路上对分时分配装置进行了实验研究和验证。分时分配的基本原理就是通过“分时”的方法,使整个分配器“空间”内的多相流都能按照给定的时间份额周期性地交替流向对应的支路,从而保证各支路内的多相流具有高度一致的相含量和确定的流量比例。实验研究证明,分时分配法具有切实的可行性,分流比等于分时比且与流量和流体的物性无关,仅取决于分配器的几何参数。     

光栅摄谱仪的改进及其在周期性极化的铌酸锂晶体倍频研究中的应用

由于电荷耦合器件(CCD)具有光谱响应范围宽、检出限低、动态范围宽、暗电流和读出噪声低以及具有积分信号、多道同时检测和实时检测等能力的优点,在光谱测量和光谱成象领域获得了广泛的应用。将传统的1m光栅摄谱仪和科学CCD相结合,使其具有实时快速测量激光光谱的能力。将其应用于宽带双包层光纤激光在周期性极化的LiNbO₃晶体(PPLN)中倍频特性的研究,观察到了倍频激光光谱随PPLN控制温度的动态变化过程,并对此进行了详细分析。     

超导太赫兹天线耦合微测辐射热检测器

超导太赫兹天线耦合微测辐射热检测器具备探测频段宽、响应速度快、灵敏度高、易于阵列化等特点因而具备广阔的应用前景.本文的主要工作是设计并微纳加工出基于氮化铌薄膜的超导器件,针对所制备器件的关键参数进行了表征.测试结果显示,当浴冷温度为4K 时,器件响应时间为4μs,噪声等效功率达到30fW/Hz0.5.基于所制备的器件进行了陶瓷刀被动扫描成像实验并取得了良好的成像效果     

Dual-mode operation of a twisted nematic liquid crystal cell by switching between dynamic and memory modes

We propose a twisted nematic liquid crystal device that can be operated in dynamic or memory mode, based on the information content to be displayed at that time. +90°-twisted and -90°-twisted states are used as two stable states for operation in the memory mode. A vertical electric field is applied to realize gray levels for operation in the dynamic mode. The proposed device has a memory retention time of over a month for the memory mode and a response time of 12 ms for the dynamic mode. Contrast ratios of over 500∶1 can be obtained in both the dynamic and memory modes.     

基于卫星共视法的电网时频测量及同步技术

时间同步对电网的安全和管理有着重要影响,如何准确可靠地同步电网时间值得研究。为此,提出利用卫星共视技术进行电网时间频率的远程校准、进而实现电网时间同步的方法。首先,提出电力系统的四级时间频率溯源体系,明确了电网时间频率溯源关系。其次,研究建立了可以满足卫星共视要求的时间频率计量标准装置,依托标准装置,将卫星共视技术应用于电力系统时间频率远程校准中,利用卡尔曼滤波算法去除干扰,并分析了基于卫星共视技术的电网时间频率同步方法。为定量评价提出方法的有效性,研究了采用提出的方法进行溯源时的时间不确定度和频率不确定度。实验及分析结果表明,提出的方法可以实现时间频率量值的高精度远程传递,从而保障电力系统中的时间同步。     

Multi-functional real-time optical processor with self-pumped phase conjugator of Cu:KNSBN

A multi-functional real-time optical processor with a self-pumped phase conjugator of Cu: KNSBN crystal is presented. The key device, self-pumped phase conjugator, has functions of both a mirror and a real-time recording medium in the processor.     

Thermo-Optical Effects and Fiber Optic Sensing Device Based on Polymer Dispersed Liquid Crystals

In this article, the thermo-optical properties of polymer dispersed liquid crystals (PDLCs) in confined geometry are experimentally investigated to demonstrate the feasibility of a fiber optic sensing device based on PDLCs.

Since an unexpected behavior of PDLCs in confined geometry has been experienced, a systematic study of PDLCs' thermo-optical properties in bulk is presented also to point out principal differences. Finally, bistable all fiber optic temperature sensors, in which a PDLC permits at the same time the opto-mechanical interconnection of two fibers and the modulation of light crossing the device, has been realized and characterized, for the first time. Being the modulation controlled by external temperature, the device has been proven to be suitable for the realization of a heat flow sensor. The sensor presents the typical advantages of both fiber optic sensors and liquid crystal technology.

Moreover, due to its small thermal capacity, it should exhibit little influence on thermal equilibrium and, above all, it represents a significant improvement compared to a temperature fiber optic sensor based on liquid crystals (presented in the literature).     

Simple high-temperature superconducting yttrium cuprate-based device for measuring weak magnetic fields

The earlier data for the magnetic properties of YBa₂Cu₃O_{7 ? x} polycrystals are used to design a highly sensitive device measuring weak magnetic fields. The sensitivity of the device is close to that of SQUIDs and much higher than the sensitivity of flux-gate meters. At the same time, the device is simpler in design and more reliable in operation than SQUIDs. Unlike SQUIDs, the device makes it possible to directly measure the magnetic field strength, has a wide measuring range, and exhibits a well-defined directional pattern.     

Applications of photorefractive crystals for optical neural networks

Photorefraction is a nonlinear optical effect in which large nonlinearities can be observed at relatively low optical power levels. This phenomenon has evolved from a laboratory curiosity to a useful device technology for optical information processing applications. In particular, the abilities to form holograms in real time and also to store thern for extended periods of time have aided the implementation of several pattern-reccgnition machines that are adaptive and possess a high degree of parallelism. This paper reviews the photorefractive effect as a device technology for the problem of pattern recognition and describes a photorefractive realization of an adaptive pattern classifier.     

A novel double quantum well device for THz range frequency detection

A novel device has been proposed which uses a double quantum well structure for the detection of signals in the THz range. The technology for the manufacturing of such devices at this point of time is significantly mature so that such a device may be easily fabricated. The detector frequency may be varied from 10 to 90 THz by changing the well widths from 10 to 30 Å.     

Membrane device for holding biomolecule samples for terahertz spectroscopy

A device for holding biomolecule samples on a membrane allows scanning using terahertz frequency waves. Such scanning has previously been difficult due to the strong attenuation of terahertz frequency waves by water. Several types of biomolecules were scanned using terahertz time domain spectroscopy (TDS), and the data showed clear differences in transmittance among the samples. This membrane device is a promising aid for research on biomolecules using terahertz waves.