保偏布喇格光纤光栅传感特性研究

对保偏布喇格光纤光栅(PMFBG)的温度和应力传感特性理论分析和实验.得到PMFGB在温度或轴向压力的作用下双峰均呈现线性变化趋势,拟合度在0.99以上,快慢轴的温度敏感系数分别为0.01189nm/℃和0.01132nm/℃,轴向应力敏感系数分别为0.00470nm/N和0.00450nm/N.结果表明,PMFBG的在温度和应力的作用下快慢轴变化速率不同,可以解决温度应力交叉敏感问题.     

基于双光栅级联结构的温度及浓度传感特性测试

研究了长周期光纤光栅（LPFG）级联布拉格光纤光栅（FBG）结构的温度及浓度传感特性。利用飞秒激光直写制作LPFG并级联FBG,且FBG波谷位于1 551.9 nm,LPFG波谷位置为1 560.5 nm。在30~50℃温度变化范围内对传感器温度特性进行测试,并在25℃超净环境下对浓度为3%~30%的葡萄糖溶液进行敏感性测试。实验结果表明:升温过程FBG中心波长发生红移,灵敏度26.36 pm/℃,线性度0.950 8;LPFG中心波长发生蓝移,灵敏度-24.55 pm/℃,线性度0.914 2。降温过程FBG中心波长发生蓝移,灵敏度25.00 pm/℃,线性度0.945 8;LPFG中心波长发生红移,灵敏度为-21.82 pm/℃,线性度0.921 2。FBG对浓度变化不敏感,当浓度由3%增至30%时,LPFG中心波长发生蓝移,灵敏度196.36 pm,线性度0.956 5。结果表明该光纤传感器灵敏度高,线性度好,可以同时动态实现温度和浓度的测量。     

磁流体包覆薄包层光纤光栅磁场传感研究

利用磁流体替代光纤布喇格光栅(FBG)的部分二氧化硅包层,制作了一种磁流体封装薄包层FBG结构的磁场传感器,研究了传感器对磁场和温度的响应特性。结果表明,在5.0～20.0mT的磁场范围内,传感器的波长灵敏度和功率灵敏度分别为34.9pm/mT和-1.063dBm/mT,波长线性响应度达到了99.2%。封装工艺未改变FBG波长随温度线性变化的特性,但受磁流体磁光效应影响,其温度灵敏度减小到9.2pm/℃。该传感器可实现磁场测量中的温度补偿,方法简单、易于实现。     

基于45°倾斜光栅对实现折射率不敏感的温度测量

利用光栅效应和保偏光纤的双折射效应相消原理, 设 计并制备了一种折射率不敏感温度 传感器。传感器由写在熊猫保偏光纤(PMF)上的倾角为45°的长周期光纤光栅(LPFG)对构 成。实验结果表明,当满足特定条件时随着环境折射率的变化,谐振波长零漂移;随 着环境温度的升高,谐振波长向长波方向漂移,温度灵敏度高达37p m/℃,高于报道的 螺旋型折射率调制级联光栅对(温度灵敏度为30pm/℃),三倍于Br agg光栅的温度灵 敏度(10pm/℃)。这种结构具有的折射率不敏感性,特别适用于生 产过程中液体的温度测量,而不必考虑折射率和温度的交叉敏感性。     

飞秒激光烧蚀长周期光纤光栅的高温特性研究

为了探索包层去除型长周期光纤光栅的高温传感特性,利用中心波长为800 nm,脉冲宽度为120 fs的飞秒激光烧蚀直写而成并对其进行高温传感检测。首先,通过两块轴线互相垂直的柱透镜将入射激光聚焦成细长焦线,并借助垂直方向CCD成像系统精确定位光纤与焦点的相对位置;然后,通过激光器内嵌shutter与运动平台的耦合控制,实现光纤光栅的精确去除加工;最后,将写制的光纤光栅置于800℃的高温炉中放置2 h。利用高温管式电热炉对所加工光纤光栅在30~1100℃内进行温度传感测试,发现其在30~300℃内谐振波长的温度灵敏度为51 pm/℃,线性度为0.956;但在高温段300~1100℃内,其温度灵敏度达到了135pm/℃,线性度高达0.999。实验结果表明,这种通过包层表面定量去除的长周期光纤光栅更适用于高温及超高温环境的传感检测。     

基于长周期光栅滤波的光栅解调系统

基于长周期光栅的边缘滤波特性,设计了一种光纤布拉格光栅的传感解调系统,适用于布拉格光栅的静态和动态解调。系统实现了3.5 nm范围内的线性解调,波长灵敏度为0.092 nm-1,波长分辨率可以达到0.01 nm。振动测量中检测信号稳定,测量频率误差在1%以内。针对长周期光栅对温度和弯曲敏感的问题,采用了适当的温度补偿和封装技术,使长周期光栅的温度漂移系数从112 pm/℃下降到45 pm/℃,显著提高了系统的稳定性。     

边孔光纤光栅的传感特性

报道了一种新型边孔光纤及边孔光纤光栅的研究结果。采用有限元法分析了边孔光纤内部的应力分布和双折射数值,并通过波长扫描技术对其双折射进行了测量,理论计算和实验测量结果表明双折射数值达到4×10-5。根据边孔光纤光栅两反射峰偏振态相互正交的特性,提出了一种基于偏振检测的波长检测方案对边孔光纤光栅的传感特性进行了测量。结果表明两峰中心波长间隔随温度变化的灵敏度仅有0.05 pm/℃,是普通单模光纤光栅温度灵敏度的1/184。提出了一种基于横向荷载压力增敏的新型边孔光纤光栅封装装置,使边孔光纤光栅双峰间距的压力灵敏度从5.6 pm/MPa增加到119.14 pm/MPa,增敏21倍,实现了温度不敏感的高灵敏度压力传感。     

采用液体腔的全光纤Fabry-Perot结构温度传感特性研究

提出并设计了一种基于液体腔结构的全光纤Fabry-Perot(F-P)传感器,对F-P传感器原理进行了研究。采用内径为0.3 mm的玻璃毛细管作为套管,将两根SMF-28单模光纤插入套管构成F-P结构,并通过在腔内填充液体进一步提高传感器的灵敏度。实验中,以空气及纯净水作为腔内介质,分别制备了光纤端面距离为119μm和123μm,反射谱周期以及条纹对比度分别为15.15 nm、14.13 nm和11.17 dBm、11.83 dBm。实验中对所制备的两种F-P传感器分别进行了温度特性的测试,在20℃的范围内,每间隔2℃对反射光谱进行采集。对于空气腔结构F-P传感器,随着温度逐渐升高,波长发生红移,特征波谷波长漂移量为2.39 nm,温度灵敏度为121 pm/℃,线性度为0.94,最大功率漂移为1.17 dBm;对于液体腔结构F-P传感器,随着温度逐渐升高,波长发生红移,特征波谷漂移量为5.31 nm,温度灵敏度为243 pm/℃,线性度为0.98,最大功率漂移量为4.07 dBm。     

基于马赫-曾德尔干涉仪的光纤光栅脉搏波解调方法

提出了一种用于智能服装中脉搏检测的光纤布拉格光栅(FBG)波长解调方法。基于光子晶体光纤(PCF)制作了一种基于模间干涉的在线马赫-曾德尔干涉仪(In-line MZI),将其作为边沿滤波器应用到FBG波长解调系统中,其温度灵敏度不超过3.5 pm/℃(25℃~60℃范围内)。实验结果表明,本解调系统能够实现2 nm范围内的线性解调,波长灵敏度为0.055 nm~(-1),波长分辨率可达2.2 pm,对FBG脉搏信号的解调结果与SM130波长解调仪的解调结果相一致。     

长周期光纤光栅构成的迈克尔逊干涉仪及其传感应用

利用高频CO2激光器刻写了性能优良的长周期光纤光栅,然后在长周期光纤光栅近端用光纤切割刀切割出一个光滑的反射面,利用该反射面与长周期光纤光栅一起构成一个简捷的在线光纤迈克尔逊干涉仪.实验研究发现干涉仪的反射谱谐振峰波长随环境温度与轴向应变线性漂移,通过解调波长的漂移量能够测量出环境温度与轴向应变.实验获得温度灵敏度为47.76 pm/℃,应变灵敏度为1.805 pm/με.设计的干涉仪结构简单,制作容易,成本低,灵敏度高,能够用于环境温度与轴向应变的测量.它在环境监测、大型建筑健康监控、工业生产等方面具有一定的应用前景.     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.