波长可选择的拉伸光纤光栅

Ｔｏｋａｉ大学工程系的学者们开发出一种用纤维光制作的光学开关 ,这种光栅能传输或反射特定波长的光。他们认为此器件在可视信号波长动态控制光信号路径的多波长光纤传输装置中可用作传输机构。光纤光栅是通过减少光纤芯部分的折射率周期变化形成的。周期性折射起布拉格光栅的作用 ,并只反射入射光的某一波长。在此试验中 ,该小组把光纤光栅一端的反射波段固定在 1550ｎｍ ,而把另一端固定在距高精密控制台的150ｍｍ处。研究人员用超发光二极管激光器使白光沿光纤传输 ,测量了反射光谱 ,同时向后渐渐移动控制台拉伸光纤。对光纤光栅的每一…     

基于色散补偿光纤的高速光纤光栅解调方法

本文提出并论证了一种光纤光栅高速解调的新方法, 利用色散补偿光纤的色散效应, 将光纤光栅的波长漂移信息转换成时域信息. 采用脉冲激光器作为光源, 仅需一个光脉冲可获取单根光纤上所有光纤光栅的反射光脉冲, 再根据各个光栅反射回光脉冲的延时变化即可实现波长的解调. 本方法可用于准分布光纤光栅传感网络解调, 系统采用全光纤结构, 无需波长扫描, 大大提高了解调速度. 本文搭建了测试系统进行实验验证, 对3个光纤光栅组成的准分布式传感网络进行了解调, 实验结果表明, 解调出的光纤光栅布喇格波长线性度好, 解调速度最高可达1 MHz, 采样数据取10次平均后解调线性度可达0.9969, 解调误差约为27.8 pm.     

用于单频光纤激光器的光纤光栅双腔Fabry-Perot结构传输谱特性理论研究

分析了基于光纤光栅的全光纤型双腔Fabry-Perot(F-P)结构传输谱特性. 理论推出了两腔F-P结构传输率具体计算公式,给出在光栅中心波长处产生单谐振传输峰时,腔长与组成光栅反射率各需满足的条件. 基于理论分析结果,分两部分数值模拟了对称及非对称两腔F-P结构传输谱,讨论了计算结果并给出定性的解释,总结了腔长及光栅长度、折射率调制深度的设计原则. 结论表明,当单腔F-P结构腔长增大到阻带内出现多个谐振峰时,通过合理选取两腔结构的腔长及光栅参数,双腔F-P结构能够在整体长度不变条件下,抑制中心波长两侧的次谐振峰,而中心波长处的主谐振峰不受影响. 关键词： 光纤光栅 Fabry-Perot结构 光纤激光器     

光子晶体光纤光栅谱特性的数值模拟研究

应用多极法理论和传输矩阵法,对基于包层空气孔为正六边形对称结构的光子晶体光纤的布喇格光栅特性进行了计算和仿真。对比研究了常规单模光纤所成光栅与相同光栅周期的光子晶体光纤布喇格光栅反射谱之间的差异,重点研究了光子晶体光纤的结构参数变化(间隙孔半径、层数)与光子晶体光纤光栅的谐振峰变化规律。当光子晶体光纤的间隙孔半径增大时,光子晶体光纤光栅的谐振波长出现蓝移;当光子晶体光纤的间隙孔径不变、层数增加时,光子晶体光纤光栅的谐振波长出现红移。     

高双折射光子晶体光纤中均匀布拉格光栅的特性

研究了具有高双折射的光子晶体光纤(HB PCF)中均匀布拉格光栅(FBG)的光谱特性。利用紧凑的超格子模型,对光子晶体光纤的传输特性进行分析,研究正向传输和反向传输的模式之间的耦合规律,从而研究写入光子晶体光纤中的均匀布拉格光栅的特性。首先给出具有C6v对称性的零双折射光子晶体光纤中光纤布拉格光栅的布拉格波长λB随光纤结构参量的变化规律;然后分析一种高双折射光子晶体光纤中的光纤布拉格光栅的光谱特性,高双折射使两个不同偏振态的反射峰分开较大;最后分析了一种常用的双模双折射光子晶体光纤中光纤布拉格光栅的光谱特性,LP01模和LPe11模的两个偏振态对应的反射谱都由于高双折射而分开。     

基于长周期光纤光栅嵌入型Sagnac环光谱的折射率测量

将长周期光纤光栅(LPG)和光纤Sagnac环相结合,实现了折射率和温度的同时测量.首先利用二氧化碳激光器在保偏光纤上制作了长周期光纤光栅(PM-LPG),然后把该PM-LPG和普通单模光纤耦合器组成Sagnac环,作为传感单元.实验选择其某一透射峰作为测试对象,其波长随温度变化,强度随折射率变化,因此可实现两个参量的...     

采用光纤光栅级联结构实现光纤延迟线

在使用光纤光栅实现皮秒级别时延的基础上,提出一种光纤光栅与单模光纤相结合的微秒级别级联结构,该结构可以实现中心波长1 550～1 553 nm范围内,间距为1 nm的窄波长反射型时延线,共1, 1.5, 2和2.5μs四种不同的时延。将单波长反射的啁啾布拉格光纤光栅与103 m单模光纤连接构成延迟单元,再利用光环形器将4个延迟单元级联并使用内半径为3 cm的光纤绕线盘,将四种延时单元的传输光纤进行整合。借助光纤光栅的反射镜作用,控制不同波长光信号通过不同的传输距离,从而达到时延目的。本文通过对啁啾布拉格光纤光栅的反射谱进行仿真分析,发现相邻反射谱的旁瓣会出现交叠现象,因此使用六个切趾函数对旁瓣滤除。结果显示：不同切趾函数的滤除效果也不同,能够完全滤除旁瓣并且对反射谱包络影响最小的是柯西切趾函数,经柯西切趾后能使不同波长光信号在对应中心波长1 nm范围内反射率达到1,而其他位置均为0。由于使用光纤绕线盘整合延迟单元传输光纤会产生一定损耗,因此对弯曲损耗进行仿真分析,结果表明：弯曲半径相同时,损耗与工作波长成正比;工作波长相同时,弯曲损耗与弯曲半径成反比。当弯曲半径大于2.9 cm时,弯曲...     

长周期光纤光栅的分析和优化设计

利用传输矩阵法对相移和变迹长周期光纤光栅的传输特性进行了计算和分析,提出长周期光纤光栅传输谱的相移优化设计方法.采用非均匀相移的设计思想,优化长周期光纤光栅的传输谱.和传统的均匀相移和变迹长周期光纤光栅相比,可以有效消除长周期光纤光栅谐振波长附近的旁瓣,并保证其传输性能.计算和分析结果表明:这种方法比传统的变迹优化设计方法更有效.     

波长可选择的拉伸光纤光栅

Tokai大学工程系的 Osamu Mikami和学者们开发出一种用纤维光栅制作的光学开关 ,这种光栅能传输或反射特定波长的光。他们认为此器件在可视信号波长动态控制光信号路径的多波长光纤传输装置中可用作传输机构。光纤光栅是通过减小光纤芯部分的折射率周期变化形成的。周期性折射起布拉格光栅的作用 ,并只反射入射光的某一波长。通过布拉格折射反射的光波长可表示为 λB=2 neffλ,其中neff为光纤有效折射率 ,λ为 n的变化周期。在此试验中 ,该小组把光纤光栅一端的反射波段固定在 1 5 5 0 nm,而把另一端固定在距高精密控制台的 1 5 0 nm处。…     

基于虚拟仪器和可调谐激光技术的光纤光栅传感系统

提出了一种新颖的基于虚拟仪器(VI)和可调谐激光技术的光纤光栅(FBG)传感系统,利用可调谐激光对由光纤光栅组成的传感器阵列进行波长扫描,实现了多根光栅的复用准静态解调,并结合抖动技术和反馈环结构,使得探测信号在每一根传感光栅中心波长处过零,以提高系统在测定波长偏移时的分辨力。当反馈环工作在闭环状态下时,该系统还可对单根光栅实现动态跟踪锁定,实现单根光栅的动态解调。该传感系统的数据采集采用虚拟仪器技术,通过多通道同时输入输出实现了在线实时解调。实验采用了4根光栅组成传感阵列,获得了静态多根光栅小于1με和单根光栅动态频率10 Hz时3.3 n/εHz的解调分辨力,动态应变范围在850με。     

Bidirectional Wavelength Reconfigurable Module Based on Tunable Fiber Bragg Grating and Remote Pump Amplifier

Abstract

This article presents a novel bidirectional wavelength reconfigurable optical network utilizing a remotely pumped erbium-doped fiber amplifier and tunable fiber Bragg gratings. The system is experimentally demonstrated at a 10-Gb/s per channel over 20-km fiber span that verifies the metro-network range system performance. The achieved power penalty is less than 1 dB when compared to the back-to-back transmission link. An example of practical application where the proposed module is used as an add/drop multiplexer and a remote node in the bidirectional wavelength division multiplexing passive optical network system is described.     

Switchable triple-wavelength erbium-doped fiber laser using a single fiber Bragg grating in polarization-maintaining fiber

A stable and narrow wavelength spacing multiwavelength erbium-doped fiber laser is proposed and demonstrated. The laser can produce simultaneous dual- and triple-wavelength lasing oscillations with a narrow wavelength spacing of less than 0.1 nm via using a single fiber Bragg gratings written in polarization-maintaining (PM) fiber. By adjusting polarization controller, the wavelength spacing of dual-wavelength lasing oscillations can be tuned to as small as 0.032 nm. The maximum amplitude variation for every lasing wavelength is less than 0.5 dB. The room-temperature operation principle is based on the polarization hole burning and deeply saturated effect in an ordinary erbium-doped fiber ring laser (EDFRL). The laser has the advantages of simple all-fiber configuration, low cost, high stability and operating at room temperature.     

光致折变布拉格光栅实验研究

本文介绍了 2 48nm、Kr F准分子激光经过石英相位掩膜版的空间调制 ,在载氢增敏处理过的通信光纤与 B/Ge光纤上分别写入光致折变布拉格光栅的实验研究。经实验测定 ,在光栅布拉格波长上 (λH2 =15 46 .45 5 4nm ,λB/Ge=15 45 .15 5 nm) ,两种光栅反射率均大于 99% ,3d B带宽分别为 0 .12 9nm和 0 .182 nm。经比较 ,B/ Ge光纤比氢载光纤具有更好的光敏性和热稳定性     

在ITU波长上的多波长光纤激光器

实验演示了一种基于半导体光放大器的多波长光纤激光器,其输出波长在ITU的波长上。使用环形腔结构,应用光纤Fabry-Perot标准具来获得ITU波长间隔,同时获得了上百条激光谱线的输出,在60nm范围的功率波动小于5dBm。     

Use of WDM technique in SDH networks

This paper proposes the introduction of the multiwavelength technique in the three layers of a SDH-based network. In the trunk layer, wavelength division multiplexing (WDM) takes advantage of the optical parallelism in a single fiber. Cross-connection can be achieved either passively (i.e., with tunable filters) or by means of wavelength converters. The latter solution, which offers high flexibility, was implemented in a 4 × 4 optical routing element. In the junction network the feasibility of a three-station WDM self-healing ring was demonstrated. Finally, in the access network, synchronous burst access and time and wavelength division multiplexing (T/WDM) switching is proposed to offer service flexibility to the subscribers.     

Torsion sensing with a fiber ring laser incorporating a pair of rotary long-period fiber gratings

We experimentally demonstrate a fiber ring laser for high-resolution torsion measurement, where the laser cavity consists of a Mach-Zehnder interferometer formed with a pair of long-period fiber gratings written in a twisted single-mode fiber by a CO₂ laser. The emitting wavelength of the laser provides a measure of the rate of the torsion applied to the grating pair, while the direction of the wavelength shift indicates the sense of the applied torsion. The narrow linewidth and the large side-mode suppression ratio of the laser can provide a much more precise measurement of torsion, compared with passive fiber-optic torsion sensors. The torsion sensitivity achieved is 0.084 nm/(rad/m) in the torsion range ± 100 rad/m, which corresponds to a torsion resolution of 0.12 rad/m, assuming a wavelength resolution of 10 pm for a typical optical spectrum analyzer. The ultimate resolution of the sensor is limited by the linewidth of the laser and could be an order of magnitude higher.     

基于偏振保持掺Er3+光纤的高稳定性单波长光纤激光器

研制出光敏偏振保持掺Er³⁺光纤,通过在这种光纤上紫外写入三个光纤光栅,形成对抽运激光高转化效率的谐振腔.在输出功率为23.617dBm、工作波长为976nm的激光抽运下,得到均值功率为9.20dBm、均值中心波长为1554.554nm的单波长激光输出.在室温下800min（约13.3h）的测量时间内,其输出功率的波动为±0.05dB,中心工作波长的波动为±0.0015nm. 关键词： 光纤激光器 3+光纤')" href="#">偏振保持掺Er³⁺光纤 光纤Bragg光栅     

Wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser based on fiber Bragg gratings

A wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser is presented by employing separated fiber Bragg gratings. By using a saturable-absorption-induced grating filter and a hybrid gain medium formed by a semiconductor optical amplifier and an erbium-doped fiber amplifier, stable single-longitudinal-mode lasing is achieved at room temperature. Wavelength spacing of the proposed fiber laser can be tuned in a range from 0.1 to 1.3 nm.     

基于光纤叠栅的全光纤声光可调谐滤波器的特性分析

本文提出了一种基于光纤叠栅的全光纤声光可调谐滤波器, 与普通光纤布拉格光栅型全光纤声光可调谐滤波器相比, 该滤波器能够对光纤叠栅的两个中心波长进行同步调制. 理论分析了声波频率和声致应变幅度对基于光纤叠栅的全光纤声光可调谐滤波器的传输光谱的影响, 结果表明, 各阶次反射峰分别以两个主反射峰为中心呈对称关系, 且主反射峰与其所调制出的次反射峰之间的波长间隔与声波频率成正比, 而两个主反射峰所调制出的同阶次反射峰之间的波长间隔与声波频率无关; 声致应变幅度主要影响主反射峰及次反射峰的反射率的变化. 实验中, 分别测试声波频率为390 kHz和710 kHz的基于光纤叠栅的全光纤声光可调谐滤波器的传输光谱, 实验结果的变化趋势与仿真分析结果相一致.     

Characteristics of Fused Optical Fiber Grating Couplers with Tapered Shapes

Fused optical fiber grating couplers (FGCs), in which Bragg gratings are written in the coupling regions of fused optical fiber couplers with tapered shapes along them are theoretically and experimentally investigated. By coupled mode analysis considering these tapered shapes, the drop efficiencies of the FGCs, which are inherently zero for the normal fiber couplers without grating, are calculated. The grating offset, which is the difference between the centers of grating and the coupler taper, is found to be effective to increase the drop efficiency of the FGC. It is determined that the tapered shapes influence the wavelength dependence of the drop efficiency and tolerate the grating offset precision. Apodizations for the grating of FGC are found to be effective in suppressing side lobes of the drop efficiency. Measurement of the wavelength characteristics of drop efficiency and the temperature characteristics of drop wavelength of the fabricated fused FGC confirm that the lightwave with specific wavelength can be dropped by the FGC and that the temperature dependence of the drop wavelength is similar to that of Bragg wavelength changes of usual fiber Bragg gratings.