基于保偏光纤取样光栅的宽频带滤波方法

提出一种新型刻录在保偏光纤上的取样布喇格光纤光栅.利用耦合模方程分析了此种光纤光栅的光谱特性,并利用切趾函数对光栅的输出谱进行了优化处理,最终可以实现高品质的宽频带多波长滤波.频带宽度为普通取样布喇格光纤光栅的2倍,经过切趾处理后,此种光纤光栅的边模抑制比也有显著提高.     

均匀光纤布拉格光栅的反射偏振相关损耗特性

研究了单模光纤布拉格光栅的偏振相关损耗(PDL)特性.运用耦合模理论和琼斯(Jones)矩阵提出了反射光的有效偏振相关损耗(PDLeff),并模拟r其随光栅参数和双折射量的变化性质.光栅反射光的偏振相关损耗在反射谱的带边处明显地表现出来,特别是带边比较陡峭时.结果表明,光栅的有效偏振相关损耗明显地依赖于光栅的结构参数和...     

聚合物太赫兹光纤布喇格光栅

研究了一种基于聚合物太赫兹光纤的太赫兹光纤布喇格光栅.通过二氧化碳激光器或紫外激光器点对点加工聚合物太赫兹光纤,实现聚合物太赫兹光纤直径的周期性调制,从而实现太赫兹光纤布喇格光栅的周期性折射率调制.基于有限元方法和光纤布喇格光栅相关理论,考虑反射峰波长、反射率、带宽、光纤长度、光纤直径和光纤直径形状变化程度等因素,研究了太赫兹光纤布喇格光栅的特性.理论模拟表明,反射峰波长和光栅周期存在与传统光学波段光纤布喇格光栅不同的非线性关系.     

用布喇格光纤光栅传感器测定口腔复合树脂材料光固化收缩与温度演化特性

复合树脂材料已成为重要的牙齿美容修复材料.本文利用两种布喇格光纤光栅传感器测定了口腔复合树脂材料在光固化过程中的收缩与温度演化特性.一种为普通的光纤布喇格光栅,另一种为经过了化学镀镍的光纤布喇格光栅,同时埋入复合树脂样品中,用光照射使其固化,测得光纤布喇格光栅在固化过程中温度和应力随时间的演化曲线.实验结果表明,在光固化过程中,因为聚合反应,树脂产生了强烈的收缩应力和温度变化.掌握复合树脂的光固化收缩特性和温度变化特性对不断改良材料性能以及优化口腔材料的治疗效果具有实际意义.     

用布喇格光纤光栅传感器测定口腔复合树脂材料光固化收缩与温度演化特性

复合树脂材料已成为重要的牙齿美容修复材料.本文利用两种布喇格光纤光栅传感器测定了口腔复合树脂材料在光固化过程中的收缩与温度演化特性.一种为普通的光纤布喇格光栅,另一种为经过了化学镀镍的光纤布喇格光栅,同时埋入复合树脂样品中,用光照射使其固化,测得光纤布喇格光栅在固化过程中温度和应力随时间的演化曲线.实验结果表明,在光固化过程中,因为聚合反应,树脂产生了强烈的收缩应力和温度变化.掌握复合树脂的光固化收缩特性和温度变化特性对不断改良材料性能以及优化口腔材料的治疗效果具有实际意义.     

基于花生形和光纤布喇格光栅结构的温度不敏感光纤曲率传感器

为了解决光纤传感器波长解调成本高以及交叉敏感的问题,提出一种温度不敏感光纤曲率传感器,该传感器是由花生形结构连接一个光纤布喇格光栅组成,对反射光采用强度解调.光进入花生形结构后激发出包层模式,通过光纤布喇格光栅反射后,反射的纤芯模再次在花生形结构产生不同阶次的包层模,然后和反射的纤芯模耦合,在反射光谱中除了光纤布喇格光栅的布喇格反射峰外,在短波长处出现若干个谐振峰,波长越小,包层模的阶次越高.实验结果表明曲率的变化范围为0.669 0~1.250 0m~(-1)时,测量到反射谐振峰平均光功率为2.260×10~(-7)~1.501×10~(-7) mW,灵敏度为-1.306×10~(-7) mW/m-1,在温度范围25℃~75℃内,反射包层模光功率基本保持不变.该传感器成本低且花生形结构制作简单、机械强度大.     

FBG滤波的级联LPFG温度和折射率传感装置

利用长周期光纤光栅具有较高的温度、折射率灵敏度,以及光纤布喇格光栅具有较高反射效率的特点,设计了一种基于光纤布啦格光栅滤波的级联长周期光纤光栅温度和折射率传感装置.利用光纤布喇格光栅的高反射率,将级联长周期光纤光栅干涉波峰的局部功率反射到功率计中,实现了温度和折射率的测量.基于信号叠加原理,对光纤布喇格光栅滤波的级联长周期光纤光栅温度和折射率传感方法的可行性进行了分析.将实际测得的功率计示数与温度以及折射率的变化进行二项式拟合,其确定系数分别为0.9990和0.9959,表明该传感方法可用于温度和折射率的精确测量.最后对该装置的稳定性做了一系列的测试,验证了该传感系统具有较高的稳定性.     

光纤光栅径向受力检测技术

对光纤布喇格光栅径向受力特性进行了理论与实验研究,给出了光纤布喇格光栅的径向受力灵敏度,并利用可调F-P标准具设计了一套解调光纤布喇格光栅反射峰劈裂值的实验系统.此系统消除了外界环境对F-P标准具初始腔长的干扰所引起的误差,系统的准确度达到了0.02 nm.     

光纤布喇格光栅沉降传感器

根据光纤布喇格光栅的光学传感原理,提出了一种基于悬臂梁及金属弹性膜片的光纤布喇格光栅沉降传感器结构,对其传感特性进行了实验研究.实验通过产生水的液位差来模拟地基沉降,分析结果显示,光纤布喇格光栅中心反射波长漂移对液位差呈现良好的线性关系,线性度高于0.999,灵敏度可达一2.11 pm/mm.通过改变悬臂梁厚度和有效长...     

光纤光栅式飞机驾驶杆杆力传感器研究

提出了一种基于光纤布喇格光栅的飞机驾驶杆力传感器.理论上讨论了飞机驾驶杆弹性元件力学特性和光纤布喇格光栅的应变传感特性,分析了飞机驾驶杆力传感器的灵敏特性.实验上通过测量不同外加载荷力作用下光纤光栅中心波长变化,研究了光纤光栅式飞机驾驶杆力传感器的传感响应特性.实验结果表明:光纤光栅中心波长漂移量和外加载荷力成线性关系,与理论分析吻合;传感器的横向与纵向灵敏度可以分别达到2.07pm.N-1和1.80pm.N-1,与数值模拟结果基本一致.     

The research on temperature measurement based on polarization dependent loss

This paper analyzes the properties of reflected polarization dependent loss of apodized fiber Bragg gratings with temperature effective. We simulates reflected spectrum and polarization dependent loss of the apodized fiber Bragg gratings. The reflected spectrum and polarization dependent loss are measured under different temperatures. The analysis results show that reflected polarization dependent loss presents two peaks which shift an equal proportion to long wavelength with temperature increasing and have very good stability so we propose an idea that use polarization dependent loss as temperature sensor measurement parameters. The results show that the accuracy of measurement can be increased almost by one order of magnitude.     

Theoretical and experimental study of differential group delay and polarization dependent loss of Bragg gratings written in birefringent fiber

In this paper, we completely study the wavelength dependency of differential group delay (DGD) and polarization dependent loss (PDL) for Bragg gratings written in birefringent fibers. Based on the coupled mode theory, we present analytical expressions for the evolution with wavelength of the transmission coefficient, the DGD and the PDL. The wavelength dependencies of these evolutions on the birefringence are then discussed. Experimental results are finally presented for an apodized FBG written in a bow-tie fiber. A very good agreement between theory and experience is reported, confirming the validity of the theoretical analysis.     

Wavelength-spacing tunable multiwavelength erbium-doped fiber laser based on four-wave mixing of dispersion-shifted fiber

We experimentally demonstrate a wavelength-spacing tunable multiwavelength erbium-doped fiber laser based on degenerate four-wave mixing in a dispersion-shifted fiber incorporating multiple-fiber Bragg gratings. We have achieved stable operation of the multiwavelength erbium-doped fiber laser, which has 0.8 nm spacing ten-channel lasing wavelengths and a high extinction ratio of more than approximately 45 dB, at room temperature. The output power of the multiwavelength erbium-doped fiber laser is stable, so the peak fluctuation is less than approximately 0.2 dB. By changing the properties such as loss and polarization state of multiple fiber Bragg grating cavities, we can exercise flexible control of the wavelength spacing of the multiwavelength output. We can also obtain switchable multiwavelength lasing operation by elimination of the effects of alternate single-fiber Bragg gratings.     

Complex fiber grating structures fabricated by sequential writing with polarization control

We propose a flexible method for fabricating complex fiber grating structures based on sequential writing for fiber gratings with polarization control of the UV source beam. Pure apodized as well as arbitrary phase-shifted fiber Bragg gratings (FBGs) can be fabricated in a single scan. Experimental examples of raised-cos2 apodized and dispersionless FBG filters are given to demonstrate the feasibility of this method.     

基于级联光纤光栅的双模外腔半导体激光器的实验研究

实现了使用两个级联的光纤Bragg光栅的外腔半导体激光器的双模运转.两个模的峰值波长取决于光纤Bragg光栅的峰值反射波长,分别为1531.5nm与1549.4nm.注入电流为53mA时,两模峰值功率达到均衡为0.5mW,边模抑制比为27dB.     

啁啾双光纤光栅群时延特性

研究了变迹线性啁啾双光纤光栅的群时延特性及其在高次色散补偿中的应用.分析表明,群时延特性与周期差ΔΛ和不同的啁啾参量C有很大的关系.研究结果表明啁啾双光纤光栅在高次色散补偿和光纤CDMA中有应用价值.     

少模光纤布拉格光栅折射率传感的分析与测量

理论分析和模拟计算了少模光纤布拉格光栅基模及高阶模的耦合与传输特性,得到在相同外部折射率变化情况下,少模光纤基模与高阶模耦合对应的布拉格波长变化,比正、反向基模之间耦合对应的布拉格波长变化显著增大.实验上制作了少模光纤布拉格光栅,测量了基模之间以及基模与高阶模之间对应的布拉格波长随外部折射率、温度变化的情况,得到与理论分析相符的结果.而对于温度变化对折射率测量结果干扰的问题,提出了通过计算布拉格波长差来克服温度影响的方法.这些结果为采用布拉格光纤光栅测量外部折射率变化提供了一种新的途径.     

A large capacity sensing network with identical weak fiber Bragg gratings multiplexing

A quasi-distributed optical fiber sensing network with large multiplexing capacity, which is based on identical weak fiber Bragg gratings, is proposed, theoretically analyzed and experimentally studied. The key technique is the demodulation technology named “Optical wavelength time-domain reflection (OWTDR),” which utilizes the optical power variation of reflected sensing signal in both time domain and wavelength domain. The influence of reflectivity of fiber grating, interval between adjacent gratings and transmission loss of delay fiber on the multiplexing capacity of sensing system are discussed. Analyzed results demonstrate that this sensing scheme can effectively increase the multiplexing capacity of sensing system up to 1000, implement multi-point synchronous measurement and reduce the cost of signal demodulation. 9 Identical weak fiber Bragg gratings with the same Bragg wavelength of 1536.651 nm, reflectivity of 6%, bandwidth of 0.07 nm are written in series to investigate the performance of the proposed scheme.     

Asymmetrically Apodized Fiber Bragg Gratings for Applications in Dispersion-Less Fabry-Pérot Fiber Cavities

Abstract

This article presents a theoretical study of the dispersion properties of the asymmetrically apodized fiber Bragg gratings. It is shown that the dispersive behavior of these gratings may be changed from normal to anomalous, depending on the apodization function and the grating strength. The asymmetrical Bessel functions were chosen in order to demonstrate these properties of the gratings. The application of this effect in a dispersion-less Fabry-Pérot fiber cavity formed by two asymmetrically apodized fiber Bragg gratings is discussed.