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。     

基于细芯光纤马赫-曾德干涉和曲率修正模型的高灵敏度光纤曲率传感器

提出了一种基于细芯光纤结合Mach-Zehnder干 涉仪的高灵敏度曲率传感器,传感头由一段细 芯光纤嵌入在两段的单模光纤中错位熔接而成。当干涉仪受到弯曲作用时,由于细芯光纤和 单模光 纤的错位熔接,使得纤芯和包层模光强度产生损耗,在一定曲率范围内使得纤芯和包层模光 强度更 加接近而导致干涉增强,通过研究特定干涉峰的干涉强度相对于曲率的变化关系,可以实现 光纤曲 率传感。为了增加曲率的校准精度,提出了一种基于悬链线法的光纤弯曲的曲率修正模型。 实验结 果表明:利用曲率修正模型修正后,在9.15m－1到11.02m－1的范围内的曲率测量灵敏度达到 142.28dB/m－1。这种基于强度变化的低成本、高灵敏曲率传 感器,具有广阔的应用前景。     

基于激光器内腔调制的低探测极限折射率传感系统

报道了一种基于光纤激光器内腔调制的低探测极限折射率传感系统。将基于单模-无芯-单模的全光纤多模干涉结构作为损耗调制器件插入光纤激光器环形腔内,采用激光器内腔调制技术获得了高灵敏度、高信噪比、窄半峰全宽的传感信号,从而实现了低探测极限的折射率测量。系统的折射率探测极限可达7.3×10-7 RIU。该传感系统具有输出稳定、温度交叉敏感小的特点,在高精度生物化学传感、海洋环境监测等领域具有一定的应用潜力。     

基于马赫-曾德干涉的保偏光纤扭曲传感器研究

实现了一种基于马赫曾德干涉原理的扭曲传感 器,其主要通过将一段15mm长的保偏光纤(PMF)两 端分别与单模光纤(SMF)错位熔接构成。PMF的扭曲会导致沿两个正交偏振态传输的 光强发生变化,从而 导致干涉光谱中共振峰的强度发生变化。通过测量慢轴共振峰在顺时针和逆时针两个方向扭 曲0～180°的强 度变化,得到传感器的最高灵敏度为0.624dB/°·m－1,是 已有类似扭曲传感器灵敏度的两倍。本文扭曲传感 器结构简单,得益于实验中采用的强度解调方法,相比于相位调制型光纤传感器,价格更 低廉,在实际应用中具有更好的前景。     

光纤马赫曾德尔干涉曲率传感器的膝关节曲率检测系统研究

在人体运动监测的过程中,膝关节运动信息在中老年慢性疾病的诊断和康复评估方面具有重要意义。研制了一种基于光纤马赫曾德尔干涉曲率传感器（Mach-Zehnder interferometer-based directional bending,MZI-BDB）的膝关节弯曲检测系统。该系统由MZI-BDB传感器、扫频激光光源、光纤耦合器、光纤隔离器、光电探测器及信号处理系统构成。MZI-BDB传感器由偏心光纤和单模光纤错位熔接而成,封装于软硅树脂片内,通过绑带固定于膝关节处。当膝关节屈曲和伸展时,诱导MZI-BDB传感器发生弯曲,传感器内透射光信号干涉场的模场状态发生变化,谐振波长发生漂移,从而对膝关节的弯曲方向和曲率进行监测。MZI-BDB传感器在正向和负向弯曲的测量角度范围为0°~90°;在正向弯曲方向上灵敏度和分辨率分别为5.29 nm/m?1和0.11 m?1;在负向弯曲方向上的灵敏度和分辨率分别为?3.11 nm/m?1和0.12 m?1。实验测试MZI-BDB传感器温度敏感度为0.043 nm/℃,该结果显示传感器对温度的不敏感特性。光电编码器与MZI-BDB传感器同时进行数据的传感采集。实验结果表明:该检测系统和光电编码器验证平台在准确度和响应度上具有一致性。     

基于保偏光栅和复合腔的单纵模双波长激光器

提出了保偏光纤光栅和复合腔结构的单纵模双波长激光器,保偏光纤布喇格光栅(PM-FBG)的波长确定了振荡频率.除了激光器谐振腔,还引入了两个滤波结构,其中一个是带有半导体光放大器(SOA)的环形滤波结构,另一个是由两个偏振分束、两个偏振控制器及一段单模光纤组成的双腔滤波器,三个谐振腔的共同作用抑制了激光器的多余纵模,得到了单纵模的线宽为4.7kHz.     

基于应变的多模光纤可调谐光纤滤波器设计

可调谐光纤滤波器技术是波分复用系统的关键技术之一,对于发展全光通信网络和光纤传感具有极其重要的意义。提出了一种基于大芯径的多模光纤可调谐带阻滤波器,其制作方法是将包层/纤芯直径为125/105μm的特种多模光纤通过单模光纤接入光纤系统,实现单模-多模-单模(SMS)光纤结构,并使一端单模光纤与多模光纤熔接,另一端只是共轴对接而不焊接。在多模干涉原理的基础上,利用该结构对应变的敏感性实现可调谐光滤波。该可调谐滤波器的调制和解调借助于放大自发辐射(ASE)宽谱光源和光谱分析仪(OSA)实现。详细给出了该滤波器的理论仿真分析,并实验证实了该方案的有效性。     

全保偏M-Z型光纤磁场传感系统实验研究

报道一种基于全保偏Mach Zender型干涉检测的光纤磁场传感系统。采用TbDyFe磁致伸缩材料,在长度约为10cm的裸保偏光纤上环绕了一层厚度约为2μm的膜,大大提高了磁致伸缩材料与光纤的附着性能,解决了光纤弯曲问题。选用保偏光纤耦合器、保偏光纤偏振器,构成包括传感部分在内的全部保偏的Mach Zender型光纤传感系统,从根本上抑制了系统偏振噪声;利用主动相位补偿法有效地消除了干涉仪系统的相位漂移。对系统的直流偏置和交流磁场响应特性进行了测试。实验结果表明,系统的相位随磁场变化的灵敏度为0.45458rad/mT,可检测的磁场分辨率达到2×10-8T。     

22 μm波段多波长可调谐光纤激光器研究

设计了一种基于马赫-曾德(M-Z)光纤干涉滤波器的可调谐多波长掺铥环形光纤激光器,M-Z光纤滤波器由两个3 d B耦合器级联构成,通过光纤耦合器接入环形腔中,并利用Sagnac光纤反射镜实现反射式滤波。实验利用一个发射功率为250 m W的1573 nm光纤激光器作为泵浦源,通过一个1570/2000 nm波分复用器(WDM)注入一段4 m长单模掺铥光纤(TDF)中获得2μm波段光增益。环形腔内加入偏振控制器(PC)调节腔内损耗,实现了2μm波段可调谐多波长输出,观测到最多3个波长激光。     

基于模间干涉的保偏光子晶体光纤弯曲传感特性研究

提出了一种基于模间干涉原理的双空气孔保偏光子晶体光纤弯曲传感方法。采用有限差分光束传播法对保偏光子晶体光纤弯曲传输特性进行了仿真研究,给出了在弯曲调制时两个低阶偏振模干涉产生的双边瓣归一化光强与弯曲半径的关系,讨论了波长变化对弯曲传感灵敏度的影响,并对所设计的弯曲传感器进行了实验研究。研究结果表明:基于模间干涉技术的双空气孔光子晶体保偏光纤弯曲传感器在10~30 mm的弯曲半径范围内具有良好的线性度和检测精度。     

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