基于熊猫光纤的高灵敏度温度传感器北大核心CSCD

本实验基于模间干涉原理制作了由熊猫型保偏光纤(Panda polarization maintaining fiber,PMF)构成的马赫-曾德尔干涉仪(Mach-Zehnder interferometer,MZI)传感器。该传感器由于大孔径多模光纤(large aperture multimode fiber,MMF)的耦合作用,对温度表现出很高的灵敏性。当外界物理量温度变化时,传感器透射谱发生漂移,通过观察特征峰的漂移与温度变化的关系,得到传感器温度响应特性。实验数据显示,该单模-多模-熊猫-单模光纤干涉仪结构的两个特征峰波长对温度线性响应,且灵敏度为-123.80 pm/℃和-195.20 pm/℃。该传感器温度实验的重复性和稳定性效果均很好,能实现对温度的有效测量。     

一种熔融拉锥型折射率和温度传感器

该文设计并制作了一种基于熔融拉锥技术的温度和折射率传感器。该结构是将一段单模光纤(SMF)两端级联无芯光纤(NCF),并通过火焰熔融拉锥技术把中间的单模光纤进行拉锥处理,从而构成了马赫曾德尔光纤干涉仪(MZI),两个无芯光纤分别充当分束器和耦合器。实验研究了该传感器对于温度和折射率的光谱响应特性,研究表明,当温度升高时,透射光谱出现红移现象,其响应灵敏度为43.96 pm/℃,线性度为0.990 5。当传感结构置于折射率1.341 6~1.382 32的蔗糖溶液中时,透射光谱强度随着折射率的增加而变大,其响应灵敏度为36668 dB/RIU,线性度为0.989。     

基于腰椎扩径熔接马赫-曾德尔干涉仪的温度光纤传感器

实现了一种基于腰椎扩径熔接马赫-曾德尔(M-Z )干涉仪的温度光纤传感器。通过腰椎扩径熔接技术,分别对4.5cm 长的单模光纤(SMF)两端进行扩径,构成球形-单模-球形结构的M-Z干涉仪。该干涉仪具 有温 度敏感特性,因外界环境温度的变化会引起光纤包层模的有效折射率发生变化,从而导致干 涉光谱的变化。 通过检测同一级次干涉谷的特征波长漂移,实现对温度的测量。实验结果表明,在温度变化 范围为15～60℃ 时,干涉谱发生了明显的红移现象,传感器相应的温度灵敏度为0.068nm/℃。本文温度光纤传感器结构简单、成本低和灵敏度高,在温度检测方面具有良好的 应用前景。     

基于表面温敏薄膜的锥形双包层光纤温度传感器

提出了一种基于温敏薄膜的锥形双包层光纤(TDCF)温度传感器,其由两段普通单模光纤(SMF)之间熔接一段TDCF组成,呈SMF-TDCF-SMF结构。由于输入端SMF纤芯模的模场与TDCF纤芯模的模场极度不匹配,因此由SMF传输过来的光除一部分耦合进TDCF的纤芯中外,其余部分耦合进TDCF的包层中以包层模的形式向前传输。当这两束光到达输出端SMF时发生干涉,形成马赫-曾德尔干涉仪。在锥区涂覆一层温度敏感薄膜,使得TDCF纤芯模和包层模之间的光程差会随着外界温度的变化而改变,从而引起传感器干涉谱的变化,因此可以通过检测传感光谱的变化实现对温度的测量。实验研究了传感器的温度特性,结果表明:随着拉锥长度的增加,干涉光谱的自由光谱范围逐渐减小。当拉锥长度为16mm,温度在32~65.3℃范围内时,随着温度的增加,传感器的传输光谱出现蓝移现象,温度灵敏度最高可达-1296.78pm/℃,且具有很好的线性度。该传感器制作简单、灵敏度高,在科学研究和工农业生产的温度测量场合具有较好的应用前景。     

硬塑料包层光纤构成的多功能光纤传感器

全光纤Mach-Zehnder干涉仪可由一段硬塑料包层光纤(HPCF)接入单模光纤(SMF)构成。由该干涉仪可以制造出光纤传感器,能对温度与折射量同时进行测量。在HPCF的透射光下,会让SMF与HPCF产生干涉谱,在外界环境温度和折射率的变化下干涉谱也会发生变化,这样就能测量温度与折射率。通过实验发现：测量温度时传感器的灵敏度为13.3pm·℃^-1,测量折射率的灵敏度为52.56nm·(RIU)^-1。该传感器因其体积小、灵敏度高的特点,能在电噪声环境中发挥重要作用。     

多芯光纤构成的温度与折射率同时测量的光纤传感器

本文设计了一种“单模光纤－多模光纤－多芯光纤－多模光纤－单模光纤”的全光 纤 Mach-Zehnder干涉仪结构。在该结构中多模光纤充当耦合器,不同模式的光在多芯光纤中 传输时将 产生光程差,形成Mach-Zehnder干涉。当环境温度和折射率变化时,通过分析干涉仪透射 光谱中不 同谐振峰的漂移量,实现折射率与温度的测量。实验结果表明,传感器低温灵敏度最高达到 46.0 pm/℃, 高温灵敏度最高达到109.0 pm/℃,折射率灵敏度最高达到54.3 nm/RIU(RIU为折射率单位)。另外, 通过同时监测传感器透射谱的两个谐振峰值波长随环境温度和折射率的漂移情况,实现了环 境温度 与折射率的同时测量,不存在交叉敏感。该传感器结构简单、制作容易、重复性好、响应稳 定、具 有多路复用功能,在传感领域有广泛的应用前景。     

光纤Michelson干涉仪型折射率和温度同时测量传感器

基于Michelson干涉仪原理,制作了一种可同时测量折射率和温度的全光纤传感器。传感器由单模光纤和一段长度为5mm的细芯光纤错位熔接而成。对该传感器的折射率和温度响应特性进行理论分析,并在折射率和温度的变化范围分别为1.333 3~1.404 9和20~90℃的环境中对传感器的响应特性进行实验研究,结果表明,随着环境折射率的变化,该传感器输出光谱峰值功率的响应灵敏度为-41.10dB/RIU,而光谱峰值波长对折射率变化不敏感;随着环境温度的变化,该传感器输出光谱峰值波长的响应灵敏度为23.15pm/℃,而光谱峰值功率对温度变化不敏感。因此,通过同时监测传感器输出光谱的功率变化和波长漂移量,可实现折射率和温度的同时测量。该传感器制作简单,测量精度高,在生物医学领域有较好的应用前景。     

基于SMS-FBG结构的温度应变双参数传感特性研究

提出了一种基于单模-多模-单模(SMS)光纤干涉结构级联光纤布拉格光栅(FBG)的光纤微结构温度应变双参数测量传感器,并对其应变特性、温度特性进行了实验研究。通过采用光纤熔接手段将长度为35.5 mm的多模光纤熔接在两段单模光纤之间,构成SMS光纤干涉结构,并通过级联FBG制成温度应变双参数测量传感器。结果证明,在200～2 000με应变范围内,单模-多模-单模干涉结构和FBG的应变灵敏度分别为-2.31和1.22 pm/με,线性度分别达到0.999 2和0.999 4;在580～700℃温度范围内,其温度灵敏度分别为58.79和13.64 pm/℃,线性度分别达到0.996 7和0.998 2,可实现温度、应变双参数的同时测量。     

基于七芯光纤的M Z双参数同时测量传感器

利用熔接机分别对单模光纤 七芯光纤 单模光纤进行纤芯错位熔接,制作了一种光纤Mach Zehnder(M Z)干涉型传感器。将一段长1 cm的七芯光纤两端分别与SMF 28单模光纤错位熔接制得M Z型干涉传感器。传感器最大条纹对比度为20 dB。分别设计不同温度、不同应变对传感器的温度特性及应变特性进行分析研究。实验发现随着温度的增加,传感器的谐振波长发生红移,40~90 ℃温度范围内灵敏度和线性拟合度分别为39.3 pm/℃和0.998 3;室温下随着应变由0增加到1 384 με,传感器的谐振波功率下降,应变灵敏度和线性度分别为0.008 8 dBm/με和0.990 3。实验结果表明,分别解调光谱的波长和光强都可实现温度和应变双参数同时测量。     

强耦合七芯光纤超模式布拉格光栅及其温度和应变响应特性研究

提出并实现了一种用于双参量同时测量的强耦合七芯光纤布拉格光栅(SCF-FBG)。在透射光谱中观察到2个布拉格谐振峰，对应SCF的类HE₁₁和类HE₁₂超模式反向谐振耦合。该传感器由SCF拼接在中心对齐的2个标准单模光纤构成，其透射谱中还包括由超模式间的马赫-曾德尔干涉产生的干涉条纹。分别测量了该器件对温度和应变的响应，结果表明：2个布拉格谐振峰的温度灵敏度分别为9.56 pm/℃和9.55 pm/℃，应变灵敏度分别为0.64 pm/με和0.584 pm/με。其中，干涉谷的温度灵敏度和应变灵敏度分别为11.8 pm/℃和-0.925 pm/με，因此该器件能够同时用于温度和应变的测量。     

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.     

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     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first