All-Fiber Optical Add-Drop Multiplexer Using a Pair of Fiber Grating Couplers

A new all-fiber optical add-drop multiplexer (ADM) using a pair of fiber grating couplers (FGCs) was proposed and first demonstrated. It was theoretically and experimentally shown that both drop and add efficiencies could be maximized in the proposed ADM. It was also clarified that the crosstalk between dropped and added signals could be improved in the proposed ADM compared with that in the single FGC. Drop and add operations in the ADM for 3-channel WDM signals with 1.6 nm wavelength spacing were confirmed. The ADM with signal amplification ability, which consists of a pair of FGCs, an EDF, and a pump-LD, was proposed and demonstrated. It was confirmed that the dropped and transmitted optical signals could be amplified in the ADM, and would be able to expand fiber routing spans.     

An ASE Reduction Filter Using Cascaded Optical Fiber Grating Couplers in EDFA Repeater

A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70% of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters.     

用统一耦合模理论分析含布拉格光栅的对称光纤耦合器的传输特性

利用由麦克斯韦方程组直接导出的统一耦合模理论分析各类型的含布拉格光栅的对称光纤耦合器的传输特性。与以前发表的分析方法不同,对于含布拉格光栅的耦合区域,统一耦合模型理论同时考虑了布拉格光栅和耦合的耦合作用。模拟结果证明它能精确地模拟和解释各种类型的含布拉格光栅的对称光纤耦合器的有关实验现象。     

莫阿光纤光栅的光谱特性及其在光分插复用器中的应用

从耦合模理论出发，结合莫阿光纤光栅的结构特性，运用分段均匀和传输矩阵法对幕阿光纤光栅的光谱特性进行了理论分析和数值计算；详细研究了线性啁啾莫阿光纤光栅的滤波特性，在此基础上，提出了一种新型的基于线性啁啾莫阿光纤光栅的光分插复用器的结构设计方案。     

一种新颖的由分插复用器构成的双向WDM网络

提出了一种新颖的双向波分复用网络结构,由多个分插复用器通过单模光纤连接而成。其中,分插复用器是基于声光效应和光纤布拉格光栅的反射特性制成的。由理论分析和实验得到的结果表明,该器件可实现一定数量信道的光信号的双向分插复用。这种双向波分复用光网络可按要求进行设计,使具有某种特征波长的光信号在设定位置的分插复用器中实现分插复用,使其按所设计的光路在波分复用网络中传输。     

Characteristics of a Grating-Folded Optical Directional Coupler

We developed a new optical add/drop multiplexer composed only of a grating-folded directional coupler. We found that in this multiplexer, the power drop becomes maximal when the grating-coupling strength is equal to that of directional coupling. At this maximum power, both power transfer between the waveguides and power reflection take place simultaneously at the grating. The power drop approaches 1 when the grating length increases.     

Characteristics of a Grating-Folded Optical Directional Coupler

We developed a new optical add/drop multiplexer composed only of a grating-folded directional coupler. We found that in this multiplexer, the power drop becomes maximal when the grating-coupling strength is equal to that of directional coupling. At this maximum power, both power transfer between the waveguides and power reflection take place simultaneously at the grating. The power drop approaches 1 when the grating length increases.     

光纤光栅和环形器组成的光分插复用器同频串扰特性研究

对三种不同结构的光纤光栅和环形器组成的光分插复用器的同频串扰进行了实验研究。实验表明，与常规的I型结构光分插复用器相比，Ⅱ型和Ⅲ型结构中由上载端泄漏到下载端的同频串扰分别减少了24．4dB和39．3dB，由下载端泄漏到上载端的同频串扰分别减少了23．6dB和24．6dB。     

非均匀光纤光栅响应特性的研究

光纤栅在未来光纤通信与光纤传感系统中将关键性作用。本文进行了不同线型光栅迹与喃啾 等波导结构参数下的非均匀光纤光栅响应特性的数值计算,并通过对光栅响应不对称性的研究讨论,提出了光栅响应对称性的两个一般条件。     

分析布拉格光栅破坏的两纤芯不同的光纤耦合器

进一步推广了描述纤芯不同光纤耦合器的耦合模理论，用于解释被布拉格光栅破坏的两纤芯不同光纤耦合器的耦合现象，理论分析的结果与已报道的实验结果相符，与单独的布拉格光栅所起的反射作用不同,这里布拉格光栅所起的作用主要是引入了强烈的色散，在光栅的频谱范围内使耦合器不再同步，在被布拉格光栅破坏的光纤耦合器的选择性频谱中，其边缘部分出现非常弱的波动，而在其阻带内出现非常强的凹陷。     

光纤光栅偏振模色散的测量及补偿研究

介绍了光纤光栅的偏振模色散测量，并利用一段偏光纤对光纤光栅的偏振模色散进行补偿，效果良好。在40Gb/s、60km光纤光栅色散补偿系统中，加入保偏光纤对光纤光栅的偏振模色散进行补偿前后的测试结果表明，误码率为10^-10时，系统的功率代价由1.21dB改善为0.46dB。     

镀金属长周期光纤光栅的研究

提出了矢量法分析和数值计算相结合的方法求解复数域超越方程来得出具有金属外包层的光纤的基模，以及包层模的传输常量。对具有复数折射率(金属)外包层的圆柱形波导(光纤)进行了分析。得出了一些规律性的结论，以此为基础分析了金属外包层对长周期光纤光栅的影响，并做了相关的实验验证。     

Underwater Acoustic Sensor with Fiber Bragg Grating

A new type of underwater acoustic sensor is proposed with an optical fiber Bragg grating (FBG). Because of the photoelasticity with respect to the refractive index and the elasticity of the fiber, the sound pressure in water modulates the Bragg reflection wavelength and, in turn, the intensity of the laser light transmitted through the FBG fiber. Good linearity between the detected signal and the sound pressure is obtained in the range from 81 dB to 140 dB re 1 μPa. Since the upper and lower limits of the acoustic signal level for operation of the sensor are limited by the driving circuit and the transduction of the sound in water, the sensor is expected to operate with much larger dynamic range both at higher and lower pressure levels. Operation of the sensor is very stable with the insertion of optical isolators into the system, although without the isolators the output signal fluctuates at low frequency due to the Fabry-Perot interference effect between the FBG and the various facets.     

窄带高反射光纤布拉格反射滤波器

利用改进的非对称六层波导模型，分析了光纤布拉格反射滤波器的特性。讨论了波导结构参数－主要是高折射率层的厚度对器件特性的影响，指出了在制作过程中控制器件反射率的途径。     

双波长啁啾相移光纤光栅

理论研究并实验验证了一种含有两段π相移的啁啾相移光纤光栅.采用F矩阵对啁啾相移光纤光栅进行计算并分析了该光栅的谱特性.含有两段π相移的啁啾相移光纤光栅可以在普通啁啾光栅透射谱阻带中产生双波长透射峰,透射峰位置直接取决于光栅中π相移的位置,透射峰的线宽和透射峰的波长间隔没有关系,仅随着啁啾率的增大而增大.采用带相位掩模的逐点扫描法对含有两段π相移的双波长啁啾相移光栅进行了制作,获得波长间隔为8 nm的双波长透射谱的光栅器件.该光栅的消光比和3 dB谱线宽分别为20 dB和0.08 nm,实验结果和理论设计一致.     

熔锥型熊猫光纤耦合器的传输特性分析

熔锥型保偏耦合器的传输特性决定了其光学原理与功能的实现。为了从理论上分析各参量对保偏耦合器传输特性的影响,基于热-结构-电磁多物理场耦合理论,建立了熔锥型熊猫光纤耦合器双锥模型,应用有限元法,分析了各参量对熊猫光纤耦合器传输特性的影响。结果表明应力区与包层折射率差影响耦合区纵向电磁场的分布,折射率差越大,纵向电磁场分布的变形也越大;HE1x1模和HEy11模的传播常量对偏振主轴角度差不敏感,偏振主轴角度差是通过耦合系数进而影响保偏光纤耦合器的消光比的;HE1x1模的传播常量对熔锥的熔锥区横截面椭圆率比较敏感,横截面椭圆率变化6.67%时Δβx11变化0.14%,计算结果表明当熔锥区横截面椭圆率为0.56时可获得较高性能的耦合器。     

基于高双折射光纤布拉格光栅的自动增益控制掺铒光纤放大器

掺铒光纤非均匀展宽引起的空间烧孔现象导致单波长激光并不能完全控制放大器增益,提出了一种新颖的自动增益控制掺铒光纤放大器的结构:即采用高双折射光纤布拉格光栅产生抽运光,其写制光栅的波峰对应的波长分别为1549.3 nm和1549.83 nm,波长间隔为0.53 nm。通过调整偏振控制器,就实现了单激光或双激光的增益控制。这种设计增益控制范围为40 nm(1530~1570 nm),当输入功率在-40~-15 dBm的动态范围内,双激光增益控制的掺铒光纤放大器的平均增益和噪声系数分别约为22.22 dB和8.69 dB,而它们的漂移分别被钳制在0.69 dB和1.51 dB。系统性能测试表明:双激光控制掺饵光纤放大器在稳定性方面比单激光有着明显的优势。     

弱耦合光纤光栅外腔半导体激光器

报道作者对单频窄宽光纤光栅外腔半导体激光器的一些研究结果。理论上分析了外腔的引入对激光器的阈值增益和光谱线宽的影响，实验上用自行研制的光纤布拉格反射滤波器（ＦＢＲ）与普通多纵模半导体激光耦合，在１．５５μｍ波段，得到边模抑制比大于２５ｄＢ，线宽小于６０ｋＨｚ的激光输出。     

一种新型的Tapered光纤光栅

利用耦合模方程对正弦型Ｔａｐｅｒｅｄ光纤光栅的反射谱进行了较为详细的计算和分析,并从实验上进行了验证。利用叠加均匀周期光纤光栅的模板和周期性振幅光栏一次成栅的方法,获得了具有三个反射峰、中心波长间隔为０．８ｎｍ的Ｔａｐｅｒｅｄ光纤光栅,这种光栅具有类似于梳状滤波器的功能,在多波长光纤激光器等方面有重要应用。     

双重光纤布拉格光栅的耦合理论分析

双重光纤布拉格光栅无论是在通信领域还是在传感领域都有着重要的应用价值。在分析双重光纤光栅折射率扰动特征的基础上,得出了它的耦合方程,并采用数值计算方法,对它的光谱特性及影响光谱特性的因素进行了系统的分析,重点讨论了两个光栅的关联特性,所用的分析方法和得到的结果对双重光纤光栅的制作和应用具有参考价值。