抗恶劣环境的保偏光纤温度传感器

基于应力型保偏光纤传输常数差对温度的敏感性并利用偏光干涉技术,提出了一种反射型保偏光纤温度传感器并推导出传感方程。在传感器中采用宽谱光源抑制了输入/输出光纤中偏振耦合引起的误差,特性分析表明这种传感器实用、精度高并且配置灵活。实验结果与理论完全吻合,其噪声等效可探测温度精度达0.01℃。根据大型电力变压器的绕组温度监测要求,研制出一套远程多路温度传感器系统。采用特殊的涂覆和密封石英毛细管封装技术,保证光纤传感头能在热油及250℃的高温下工作,而且具有很高的绝缘性。检测结果表明传感器在0~200℃内,达到了±0.5℃测量精度。     

基于保偏光纤模式干涉的温度传感技术

基于Sagnac光纤干涉仪偏振非互易的光纤温度传感器的理论、方案和相关技术,利用光强度直接测量的信号检测技术,实现了单点温度传感并进行了实验验证.实验和测试表明:这种温度传感器达到了0.01℃的温度分辨率和稳定性,通过改变温度传感头的长度和传感保偏光纤的双折射率,可方便地调节其测量范围.同时又提出了一种新的反射型保偏光纤温度传感方案并研制出微小型保偏光纤温度传感头.在此基础上,实现了多点温度测量,研制出大型变压器绕组温度监控用多点温度传感系统,在0～200 ℃的温度范围内达到了0.5℃的测量精度和分辨率,研制的传感头满足高电压绝缘和热油、热蒸汽的恶劣环境要求.     

反射型保偏光纤温度传感器现场校准方法

设计了一种反射型保偏光纤温度传感器,介绍了其原理并给出了传感方程。分析表明:光路传输损耗变化是引起传感方程参数变化的主要原因,在需要重装光路的应用场合,需要对传感方程参数进行现场校准。结合输出信号和传感方程系数的特点和关系,将传输损耗与传感器本征参数分离,提出了一种简单实用的现场校准技术并建立了计算模型。采用该技术,在校准时只要给出传感头所处位置的一点温度值便可实现传感方程所有参数的校准。搭建了实验系统,通过改变光路传输损耗进行了校准实验,分别采用曲线拟合和模型计算方法进行了数据分析和对比,对该方法进行了验证。实验表明,在-30～60℃的温度范围内,校准前后温度传感器的精度均可达到±0.5℃。     

一种高精度补偿式双折射型光纤温度传感系统

提出一种新型的偏振调制光纤传感器的补偿技术，用于双折射型光纤温度传感器系统，传感探头使用同一偏振分光棱镜既作为起偏器，又作为检偏器，采用反射式光路，使系统具有简单、可靠、实用的特点。实验结果表明：采用这种补偿技术的光纤传感器具有较好的测量精度和长期稳定性。     

光纤光栅温度传感器增敏封装特性研究

通过利用聚酰亚胺涂覆裸光纤光栅的方法研制了一种增敏型光纤光栅温度传感器,其反射波长的温度敏感系数由曾敏前的10pm/℃提升至40pm/℃。在-40~200℃测试环境中,开展了传感器标定和温度精度测量试验。试验结果表明:利用光纤光栅增敏封装,在高低温环境中采用低精度光纤光栅解调仪,传感器的测温精度由±0.4℃提升至±0.1℃。上述结果显示,采用增敏封装结构能够提升光纤光栅温度传感器的测量精度,减低制作成本。     

基于游标效应的萨格纳克干涉仪温度传感器

提出了一种基于光学游标效应的级联光纤萨格纳克干涉仪和光纤模态干涉仪高灵敏度温度传感器，并对其传感特性进行了实验研究。光纤萨格纳克干涉仪由一段保偏光纤和3 dB四端口耦合器组成，光纤模态干涉仪由一段少模光纤与两段单模光纤熔接形成。选取光纤萨格纳克干涉仪作为温度传感器，光纤模态干涉仪充当滤波器。通过控制保偏光纤和少模光纤的长度，使光纤萨格纳克干涉仪的自由光谱范围为2.63 nm,光纤模态干涉仪的自由光谱范围为2.82 nm,两者的自由光谱范围相近又不相等，从而形成光学游标效应。实验结果显示，单个光纤萨格纳克干涉仪的温度灵敏度为-1.30 nm/℃,级联光纤模态干涉仪后，其温度灵敏度提高到-18.19 nm/℃,放大倍数为13.99。该传感器制造工艺简单，稳定性好，不需要特殊的增敏材料来提高灵敏度。     

基于光纤激光器内腔调制的温度传感系统

本文报道了一种基于光纤激光器内腔调制的温度传感系统。将基于单模-保偏-单模(SPS)的光纤Sagnac干涉结构作为滤波和温度传感器件插入光纤激光器内腔中,采用激光器 内腔调制技术实现了高分辨率的温度测量。传感系统的输出信噪比(SNR)可 达到59dB,半 高宽(FWHM)小于40 pm,在40 ℃温度范围内的灵敏度为0.641 mW/℃,温度分辨率 达到了1.56×10－6 ℃。传感系统具有结构简单、输出稳定的 特点,有望应用于工业生产、环境监测、海洋科学研究等领域。     

基于波长与强度双解调的光纤温度传感器

为了更好的了解光纤传感原理,并提高温度光纤传感器的各方面性能,提出一种新型的具有波长与强度双解调的光纤温度传感器。将30mm的保偏光纤(PMF)的两端分别与单模光纤(SMF)进行腰椎放大熔接,形成两个腰椎,构成全光纤马赫泽德尔(M-Z)温度传感器。温度的变化将会引起光纤的纤芯模与包层模相位差的变化,从而导致干涉光谱的变化。以25-70℃作为测试温度,通过光谱仪(OSA)监测宽带光源经传感器后的干涉光谱。实验结果表明,温度升高,特征峰波长在向长波长方向移动,并且其强度在逐渐增大。因此,采用波长与强度双解调的方法对温度进行测量,其灵敏度分别为0.127nm/℃和0.32dB/℃,对应的分辨率分别为0.16℃和0.03℃。这个双解调的全光纤温度传感器制造简单、成本低、体积小和结构稳固,而且具有很高的分辨率,因此适用于实际测量。     

一种用于海洋温度快速测量的光纤法布里-珀罗温度传感器

为满足海水温度高精度快速测量的需求,提出了一种基于光纤法布里-珀罗(F-P)传感器的温度传感方案。该传感器由硅片和光纤尾纤组成,硅片作为光纤F-P传感器F-P腔的腔体,利用硅的热光效应和热膨胀效应实现温度的传感。采用基于二分法的交叉相关快速解调算法对光纤F-P传感器进行高精度的快速解调。对制作的光纤F-P温度传感器进行测试,结果表明:该传感器可达到0.15℃的温度测量精度,可分辨0.001℃的温度变化,温度响应时间可达到128ms。该传感器有望在投弃式测量领域得到应用。     

卫星镜头结构光纤光栅温度传感器研究

为了解决卫星星敏感器光学镜头结构在轨温度监测问题,提出一种弧形基底封装的光纤光栅温度传感器。分析了星敏镜头结构特征与光纤光栅温度传感原理,采用飞秒激光刻写的光纤光栅作为敏感元件,设计了可贴合于星敏镜头结构特征的弧形封装基底,完成了光纤光栅温度传感器封装,并对传感器进行了拉伸测试、温度标定及温度重复性测试,并已应用于实际工程中。结果表明:弧形封装结构形式的光纤光栅温度传感器线性度可达0.998,温度灵敏度达到8.54 pm/℃,同一温度下中心波长变化量在2 pm以内,且受弧形基底封装结构变形产生的应变影响小。卫星在轨温度监测,光纤光栅传感与电子式传感相差±3 ℃。可以实现星敏镜头结构的温度测量功能,在星敏感器结构在轨温度测温中具有应用前景。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks