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.     

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.     

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。     

利用调谐滤波技术的光纤光栅复用传感器

采用光纤光栅悬臂梁线性调谐技术 ,提出了利用调谐滤波技术对光纤光栅复用传感信号进行检测的方案 ,在分析其基本工作原理的基础上 ,实验研究了其波分复用传感特性 ,传感测量的结果与光谱分析仪直接测量的结果基本一致。传感器的波长分辨率主要取决于系统的最小可探测光功率 ,由于采用了高灵敏度的光电测量系统 ,传感测量的波长分辨率可达 0 .0 0 5nm ,应变分辨率可达 5.7× 10 - 6 。     

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。     

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。     

基于光纤环形激光器和光放大的100 km光纤布拉格光栅传感系统

在基于掺铒光纤-拉曼混合放大的可调光纤环形激光器的光纤布拉格光栅(FBG)传感系统结构基础上,提出了延长传感距离的新方法。该方法以环形掺铒光纤激光器作为光源,采用双波长拉曼放大的方法对信号进行低噪声的双向放大,系统中间的两段掺铒光纤再利用剩余的抽运功率产生自发辐射光和放大传感信号,使得整个系统能够在超长的传感距离上获得很高的信噪比。实验表明使用一只40 mW的掺铒光纤放大(EDFA)抽运源、一只170 mW的拉曼抽运源和一只2 W的拉曼抽运源,可以使整个系统的传感距离达到100km,并且传感系统的光纤布拉格光栅反射信号均能获得超过57 dB的优良信噪比,从而实现在超长距离上的光纤布拉格光栅传感。     

Multiwavelength Linear-Cavity Fiber Laser Source Using a Sagnac Interferemetric Filter and a Strain-Induced Chirped Fiber Grating

A novel multiwavelength linear-cavity fiber laser source using a strain-induced chirped fiber Bragg grating, a Sagnac interferemetric filter, and Erbium-Ytterbium codoped fibers is proposed and demonstrated for the first time. The Sagnac interferemetric filter, which acts as a full-reflecting mirror, consists of a polarization-maintaining directional coupler and two pieces of polarization-maintaining fibers. The strain-induced chirped FBG, which acts as a partial-reflecting mirror, is achieved by bending a uniform FBG bonded at a slant onto the lateral surface of a simply supported beam. By tuning the strain-induced chirped FBG, desirable lasing wavelength and number can be easily achieved.     

啁啾光纤光栅在光纤通信系统中的色散补偿

报道一个简单而新颖的、能将均匀光栅改变为线性啁啾光栅的方法,此方法可对光纤光栅的喃啾度和中心波长进行独立调节,实验表明,一长为１０ｃｍ的均匀光栅其啁啾度可增加至０．５ｎｍ／ｃｍ,而中心波长独立可调量达０．７ｎｍ利用这样的可调啁啾光栅在标准单模光纤（Ｇ６５２）中对一脉宽为２５ｐｓ的输入信号在１５５０ｎｍ窗口传输,成功地实现１００ｋｍ的色散补偿。     

4×10 Gb/s 412 km密集波分复用光纤光栅色散补偿的实验

研制了一种多波长啁啾光纤布拉格 (Bragg)光栅 ,波长、波长间隔符合ITU T标准 ,利用这种多波长啁啾光栅可以同时对多信道波长进行色散补偿 ,光栅的每个波长补偿范围满足ITU T对应信道波长波动的要求 ,并进行了 4× 10Gb/s、4 12km波分复用色散补偿实验 ,实验结果比色散补偿光纤模块要好 ,无误码功率代价都小于 2dB。     

980nm单模运转未镀增透膜光纤光栅激光器

提出了一种工艺简单的980nm未镀增透膜的光纤光栅外腔半导体激光器。首先从理论上分析了边模抑制比(SMSR)与激光二极管前表面反射率R2、外腔长Lext和激光二极管一光纤耦合效率之间的关系,得出边模抑制比随R2和Lext的增大而减小,而随着激光二极管一光纤的耦合效率的提高而增大。从计算结果中还可以看出,即使半导体激光器不镀增透膜(R2=0．3时)。在其它参量合适的情况下,边模抑制比仍可大于40dB。然后,对其进行实验验证。在半导体激光器未镀模的情况下,选择光纤光栅发射率为0．5,外腔长为12．5cm,输人电流为28．8mA(约为阈值电流的2．4倍)时,通过仔细调节恒温、恒流电路,实现了边模抑制比高于40dB的稳定的单纵模输出,外腔激光器的线宽优于1．6MHz。     

Transmission Performance Improvement in Microwave/Millimeter-Wave Optical System Using Chirped Fiber Grating

A chirped fiber grating (CFG) written by the moving fiber/phase mask scanning beam technique with a uniform mask is used to demonstrate the dispersion compensation in the externally modulated microwave/millimeter-wave over fiber system. It is found that the use of the CFG is an efficient way to compensate for the severe RF power degradation induced by the fiber chromatic dispersion, which results in a significant improvement in the transmission performance. The signal to noise ratio is improved from 4.8 dB to 24.4 dB when 10.58 GHz RF signal carrying 5 Mbit/s QPSK format data is transmitted over 35 km single mode fiber.     

一种准分布式光纤光栅漏油传感器

分别对两种结构的传感头组成的分布式光纤Bragg光栅漏油传感器进行实验后得出,具有限位装置的传感头组成的传感系统综合性能好于由另一种结构传感头组成的传感系统。具有限位装置的传感头不仅有较好的漏油检测响应性能,而且能防止相邻信号间的串扰,同时能很好保护光纤光栅不被拉断,更重要的是它受温度干扰较小。     

侧面压迫式及端面拉伸式增敏光纤光栅水声传感器

研究了采用侧面压迫式增敏和端面拉伸式增敏的无源光纤光栅水声传感器。采用灌注和弹性片端面增敏两种方案分别对光纤光栅传感器进行增敏。研究结果表明灌注方案谐振频率过低(300Hz),高频灵敏度过低(小于-205dB),且制作工艺要求比较复杂;弹性片端面增敏方案采用铍铜片进行增敏,在100～1000Hz频率范围内灵敏度为(-175±2)dB。对端面增敏传感器进行了封装,并应用于水声的检测实验。实验表明,该传感器在灵敏度及灵敏度频响指标上已经可以满足应用要求。     

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.     

光纤光栅时延波动对传输系统性能的影响

对啁啾光栅的时延波动进行了详细的分析，建立了时延波动的简易模型和光栅的滤波函数。大量实验和计算表明，光纤光栅的时延纹波周期在0．01～0．1nm之间，并且在光纤光栅的阻带内，时延纹波周期随波长增大而逐渐增大。利用薛定谔方程对时延波动对系统的影响进行了仿真，得出了时延波动对系统的影响不仅与波动大小有关，而且还与时延波动周期有关，并用实验进行了验证。     

基于波分耦合器的光纤布拉格光栅传感器

为了实现对光纤布拉格光栅传感器的波长解调,使用普通的光纤波分耦合作为波长鉴别器件,将波长的变化转变成光强的变化,并用双路差动放大去除光源强度变化和外界干扰的影响。使用发光二极管(LED)作为光源以降低系统成本,因此使用调制光源和交流放大器对信号进行处理。实验达到约10με的应变测量分辨力和0．2℃的温度测量分辨力。是目前最廉价的光纤布拉格光栅传感器之一。     

基于超结构光纤光栅的全光编解码性能分析

分析了光码分多址(OCDMA)系统中超结构光纤光栅(SSFBG)编解码器的相关特性, 考虑了输入脉冲宽度、SSFBG编解码光栅之间的波长偏移以及光栅的折射率调制振幅对全光编解码性能的影响。结果表明, 随着输入脉冲宽度和编解码光栅之间的波长偏移量的增加, 自相关峰值旁瓣比和自互相关峰值比下降, 即编解码性能出现下降; 编解码器的插入损耗和相关性能间存在矛盾, 需要折中考虑SSFBG折射率调制振幅的选取。建立了基于SSFBG编解码器的时域相位编码OCDMA系统的数学模型, 考虑了差拍噪声、多址干扰、接收机噪声以及接收机的带宽限制对系统性能的影响, 采用全光阈值技术和turbo编码来提高相干扩时OCDMA的系统性能。     

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。     

掺铒光纤放大器在多路模拟光纤传输系统中应用

对应用掺铒光纤放大器的副载波频分复用模拟电视光纤传输系统的噪声和失真进行了实验研究，利用掺铒光纤放大器作为系统的功率提升和中继放大器，分别成功地进行了１８５ｋｍ和２１５ｋｍ的系统传输试验