光纤光栅特性及其在光通信中的应用

光纤光栅是一种极其重要的光纤无源器件,介绍光纤光栅的光学特性,并对应用于光通信系统中的高性能光纤光栅器件,如OADM、滤波器、色散补偿器、激光器等的原理及应用进行阐述。     

光纤Bragg光栅的特性及应用研究

介绍了光纤光栅研制及其应用研究的情况。研究包括：光纤光栅的基本特性,光纤光栅外腔半导体单频和锁模激光器、光纤光栅稳频光纤环形激光器和主动锁模光纤激光器、基于光纤光栅的波长转换器和基于啾啁光纤光栅的可调谐激光器等。     

基片式高灵敏度光纤光栅温度传感器

光纤光栅是一种新型光学无源器件,现已普遍运用于传感测量方面,但由于裸光纤光栅的灵敏度比较低,需要对其进行增敏封装处理。该文提出一种基片式封装结构,运用铝和殷钢两种不同热膨胀系数的材料,进行过渡配合,当铝受热产生变形,在铝和殷钢之间形成挤压力,这种挤压力减弱横向延伸,增强纵向两端延伸,使得光纤光栅应变增大。通过水浴加热实验对比分析裸光纤光栅、封装的光纤光栅和改进封装后的光纤光栅的温度特性,实验结果表明改进的基片式封装结构温度传感器的线性相关系数为0.996,其灵敏度为33.21 pm/℃,是裸光纤光栅的3.224倍,比单一铝材料封装灵敏度增大6.41 pm/℃,可广泛运用于多种场合的温度测量,具有实际的应用价值。     

柱面透射光栅的衍射特性

从理论上分析了较高空间频率的柱面透射光栅的衍射特性，在不作近似的条件下，用计算机模拟出了不同曲率半径的柱面透镜组成的柱面透镜组成的柱面透镜光栅的夫琅和费衍射特性，得出了共衍射光强的分布规律。光学实验给出了由光学塑料制成的空间频率为１０ｌｐ／ｍｍ的柱面透射光栅的衍射光强分布。计算机模拟结果与光学实验结果吻合。     

光纤结构对参考光栅温度补偿误差影响

光纤光栅的温度传感特性是与其实际结构组成相关的。在现有的参考光栅温度补偿方法中,大都没有考虑温度参考光栅的结构影响问题。本文通过力学分析和数学仿真计算对涂覆、套塑光纤光栅的实际温度响应特性进行了研究。推导得出了与光纤结构相关的光栅温度传感特性公式,并首次给出了光纤结构在参考光栅温度补偿法中引入误差的定量分析方法。本研究有助于根据测量结果对被测结构的应变状态进行更为准确的评价,也为实际应用中合理选择温度参考光栅的涂覆层参数提供了有力的理论依据。     

光纤布拉格光栅温度传感特性与实验研究

从光纤布拉格光栅温度传感模型出发,对光纤布拉格光栅温度传感的理论进行了分析,并通过实验对裸光栅的温度特性进行了研究,推导出了光纤布拉格光栅温度传感的一阶有效线性灵敏度系数的解析式.实验结果表明,光纤光栅在所测温度范围内具有良好的线性特性,与理论结果基本一致.表明光纤光栅温度传感的理论模型具有良好的实验基础.     

光纤布拉格光栅温度传感特性与实验研究

从光纤布拉格光栅温度传感模型出发,对光纤布拉格光栅温度传感的理论进行了分析,并通过实验对裸光栅的温度特性进行了研究,推导出了光纤布拉格光栅温度传感的一阶有效线性灵敏度系数的解析式。实验结果表明,光纤光栅在所测温度范围内具有良好的线性特性,与理论结果基本一致。表明光纤光栅温度传感的理论模型具有良好的实验基础。     

FBG智能传感器及其在土木工程中的应用研究

光纤光栅传感器已经越来越得到土木工程界的认可,并应用到了实际工程.针对大型土木工程结构长期健康监测的变形监测需要,在光纤光栅传输理论的基础上,分析了光纤光栅应变与温度传感特性以及光纤光栅应变传感的温度补偿原理和方法;研制开发出满足工程应用的光纤光栅封装传感器、FRP-OFBG复合智能筋、光纤光栅智能拉索;此外,考虑传感器开发和工程应用的需要,研究了光纤光栅应变传感的界面传递机理和误差修正.最后,建立了光纤光栅智能监测系统,并成功地将光纤光栅传感器应用到实际桥梁结构的施工与运营监测.     

一种简易测试光纤光栅应变测量系统的方法

针对光纤光栅应变测量系统应用测试问题,基于悬臂等强度梁应变实验,对比理论计算、光纤光栅应变传感器及电阻应变片的三种应变测量方法,得出光纤光栅应变测量系统具有较好的可靠性和准确性。以国外可靠光纤光栅应变测量系统为参照,提出了简易测量光纤光栅应变传感器和光纤光栅传感分析仪性能的方法。针对准分布式监测问题,主要分析了光分路器对光纤光栅传感应变测量的影响。上述分析为光纤光栅应变测量系统在工程中的应用提供充分依据。     

基于光纤传感器的输油管道远程安全监测系统研究

鉴于Bragg光纤光栅传感器的温度和应变敏感特性,将其引入远程安全监测系统,设计开发确保油气管道安全传输的远程监测系统。该系统设计包括硬件部分和软件部分,其中硬件设计主要是对光纤光栅传感器、信号解调与分析、数据通信与传输、数据处理与分析中心四大系统的详细设计;软件设计采用LabVIEW语言编程,实现动态监测和实时分析两大功能。试验表明该系统有助于确保输油管道安全运行,工程实用价值较高。     

制作光纤光栅的相移掩模-双光束干涉曝光方法

介绍将无铬相移掩模技术和双光束干涉曝光技术用于制作纳米级图形光纤光栅的基本原 理和实验系统设计。提出一种用可移动反射镜使写入光束扫描固定在一起的相移掩模和光纤组合体制作光纤光栅的方法,既便于系统调整,增强曝光能量,又可方便制作高分辨力、长尺寸光纤光栅,无论是周期光栅,还是非周期光栅。     

Distributed light delivery and detection via single optical fiber and tilted grating

A passive fiber-optic-based device is designed and analyzed, capable of delivering and detecting light separately or simultaneously at discrete points of interest along the optical axis of a fiber. This goal is achieved by implementation of multiple finite-length tilted gratings inside the core of a single-mode fiber. Each grating is tuned to function as a leaky electromagnetic resonator that resonates at particular wavelength and partially radiates the optical power to the medium surrounding the fiber. First, the basic element of such radiators is theoretically analyzed and a sequence of justifiable approximations are presented to measure the characteristic parameters of the system. Next, a set of equations are developed to provide a logical procedure for the design. This device has several potential applications in the field of fiber optic sensors. Few practical examples of such applications, particularly for optical stimulation of cells and fluorescence signal recording in sensitive tissues including the brain, are studied.     

光纤光栅视觉系统

利用光学衍射原理，研制成了光纤光栅衍射屏，并与计算机神经网络相结合，开发了了一种识别立体形状的视觉系统。本文介绍了光纤光栅的设计原理及计算方法，给出了系统的总体结构及工作原理，完成了三棱 柱，三棱锥、四棱柱，四棱锥和球等立体形状学习与识别，并讨论了实验结果。     

Modeling, design, fabrication, and testing of a fiber Bragg grating strain sensor array

The modeling, design, simulation, fabrication, calibration, and testing of a three-element, 15.3 cm fiber Bragg grating strain sensor array with the coherent optical frequency domain reflectometry (C-OFDR) interrogation technique are demonstrated. The fiber Bragg grating array (FBGA) is initially simulated using in-house software that incorporates transfer matrices. Compared to the previous techniques used, the transfer matrix method allows a systemwide approach to modeling the FBGA-C-OFDR system. Once designed and simulated, the FBGA system design is then imprinted into the core of a boron-germanium codoped photosensitive fiber using the phase mask technique. A fiber optic Fabry-Perot interferometric (FPI) strain gauge calibrator is then used to determine the strain gauge factor of a single fiber Bragg grating (FBG), and the results are used on the FBGA. The FPI strain gauge calibrator offers nondestructive testing of the FBG. To test the system, the FBGA is then attached to a 75 cm cantilever beam and interrogated using an incremental tunable laser. Electric strain gauges (ESGs) are then used to independently verify the strain measurements with the FBGA at various displacements of the cantilever beam. The results show that the peak strain error is 18% with respect to ESG results. In addition, good agreement is shown between the simulation and the experimental results.     

光纤望远系统设计

结合以大截面光纤传象束作为中继传象元件的光纤望远镜研制，阐述了光纤望远系统的组成和成象原理；提出了为实现系统具有较高的光学性能，良好的传象质量，在设计上应作的考虑和措施，其中包括系统光学参数确定和结构的选择，此外，还讨论了光纤望远系统中的一些特殊问题，如光束限制，调焦及象质改善等。     

改进型双光栅矩阵运算光纤光栅传感器

在光纤光栅传感器的应用中一直存在着交叉敏感问题,必须采取各种措施进行补偿或区分。 在悬臂梁的上下两面分别粘贴光纤光栅,通过分别测量这两个光栅的波长位移的改进型双光栅矩阵运算法来克服交叉敏感问题。该方法只需要一套光源和检测系统,装置简单,具有较低的成本和实际应用前景。     

应用于全光网络的取样布拉格光纤光栅Interleaver设计

基于取样光纤布拉格光栅(SFBG)的光Interleaver能将一路光信号解复用为两路奇偶波长信号,具有插入损耗低、各信道反射率均匀和低色散等优点,特别适用于未来全光DWDM中波长复用/解复用、插入/分离。为此介绍了取样光栅Interleaver的基本设计理论,给出了设计实例,对取样光栅Interleaver等光器件的实用化有一定的参考意义。     

Response of fiber Bragg gratings to longitudinal ultrasonic waves

In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for meeting specific requirements in terms of field intensity and frequencies.     

用于低能X射线段的掠入射光栅摄谱仪

介绍一种新颖的用于研究激光等离子体的掠入射光栅摄谱仪。掠入射光栅摄谱系统由三部分组成：掠入射光栅摄谱仪、四维精密微调装置和一个含光纤传象束、摄象机、监示器和激光准直仪等构成的瞄准系统。文中论述了掠入射光栅摄谱仪的光路设计、机械设计特点和性能实验结果。     

Full vectorial modal analysis of specialty fibers and their Bragg grating characterization

Optical fibers and specialty waveguides are the bases of the majority of today's telecommunication, biomedical, sensing, and light-delivery applications. Modal analysis plays an important role in optimizing the optical performance of these fibers when they are integrated with optical systems. We present a full vectorial modal theoretical analysis of specialty cylindrical symmetric fibers with arbitrary index profiles, using a staircase approximation and scattering matrix approach with no constraints on the refractive index profile. We demonstrate the generality of this method by investigating the modal characteristics of two specialty fibers: graded-index fiber and concentric-shell multicore fiber. The calculated modal effective indices for the graded-index fiber are compared with those calculated by the WKB method, stressing the main differences between the scalar and vectorial approaches. Using the same approach, we calculate the Bragg grating response of a holographic grating written in the guiding regions of a concentric-shell fiber and compared them with experimental measurements.