纤维光学 光纤器件

TN253 2005031975 利用线性啁啾光纤光栅补偿PMD的实验研究=Experi- mental research on PMD compensation using linearly chirped fiber Bragg grating[刊,中]／张霞(北京邮电大学理 学院．北京(100876)),黄永清…∥半导体光电．-2004, 25(4)．-293-295 对利用线性啁啾光纤光栅补偿偏振模色散(PMD)进 行了实验研究。利用压电陶瓷的压电效应挤压线性啁啾 光纤光栅使之产生双折射,用于补偿光通信系统中的偏振 模色散。通过改变施加在压电陶瓷上的电压值,可实现对     

基于变截面梁的光纤光栅线性无啁啾调谐

从理论上分析了利用变截面（等强度）弹性梁实现光纤光栅波长线性、无啁啾调谐的基本原理,给出了实现无啁啾波长调谐的弹性梁截面满足条件及其设计方案,并讨论了矩形等截面和变截面悬臂梁调谐方案的特点.理论分析与实验结果均表明,通过对变截面梁侧向施加载荷,可以实现光纤光栅中心波长的线性无啁啾调谐,且系统结构简单、易于设计.     

线性啁啾莫尔光纤光栅的理论研究

以经典耦合模理论为基础,结合线性啁啾莫尔光纤光栅的结构特性,给出了线性啁啾莫尔光纤光栅的耦合系数和耦合模方程,并用龙格库塔迭代法数值求解耦合模方程.对多种线性啁啾莫尔光纤光栅的光谱特性和时延特性进行了理论模拟.分析结果表明,线性啁啾莫尔光纤光栅的相移特性和切趾特性,使得该类型光栅在波分复用全光网中有着很好的应用前景.     

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。     

新型光纤光栅中心波长与带宽独立调谐方法

提出了一种新型光纤光栅中心波长与带宽独立调谐方法，将光纤光栅沿圆柱形弹性梁的轴向成一定角度粘贴于侧面，通过改变梁的扭转角与侧向位移，实现了光纤布拉格光栅中心波长与带宽的准线性独立调谐，实验上获得了8．28nm准无啁啾波长调谐和5．32nm准无中心波长漂移的带宽调谐，实验结果与理论分析一致.     

一种新型的光纤光栅封装装置

介绍了一种新型剪刀形封装装置,并利用其进行了光纤布拉格光栅的温度补偿实验.这种封装结构保持了光纤光栅体积小的优点,同时无需给光纤光栅施加预应力;封装后不产生啁啾,并可与压电陶瓷结合,扩展光纤光栅布喇格波长的调谐范围;应变量的调节只跟金属丝有关,与支架的材料无关,从而大大简化了设计.在－30℃~80℃温区,温度灵敏度降低10倍以上,达到0.001 nm/℃,符合光纤通信要求.     

啁啾光纤光栅透镜法制作技术的理论与实验研究

对利用零级抑制均匀相位掩模版结合同透镜制作啁啾光纤光栅的技术进行了详细的理论和实验研究。结果表明这种方法适合于制作啁啾参数较小的光纤光栅，当所制作的光栅啁啾参数较大时，将导致严重的光谱不对称性和包层模耦合。     

三次啁啾光纤光栅的设计及其应用

针对直接调制的半导体激光器产生的非线性啁啾,设计了一种新型的三次啁啾光纤光栅,与线性啁啾光纤光栅相比,它能更为彻底地补偿此类非线性啁啾.     

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。     

线性啁啾长周期光纤光栅用作EDFA增益平坦滤波器的理论研究

提出用具有特定折射率调制包络的线性啁啾长周期光纤光栅作为掺铒光纤放大器(EDFA)的增益平坦滤波器.采用龙格库塔迭代法数值求解该类型光栅耦合模方程,就特定的掺铒光纤放大器增益谱,用Nelder-Mead优化算法对光栅结构参量(光栅长度、周期、线性啁啾系数、折射率调制包络的形状等)进行优化,设计出能在C波段35 nm带宽范围内对掺铒光纤放大器进行平坦化(增益起伏在±0.5 dB之内)的平坦滤波器.     

基于非线性啁啾光纤光栅实现的色散可调谐

从原理上证明了一种基于非线性啁啾光纤光栅以及光纤光栅的温度特性的色散可调谐方案.实验证明在25.5℃的温度变化范围内,光纤光栅对1550.43nm波长的色散补偿量从759.1ps/nm上升到1659.9ps/nm,色散调谐范围达到900ps/nm,这个方案具有对补偿波长和特定补偿波长所需要的色散补偿量同时进行调谐的特点.     

一种新颖的高灵敏度光纤光栅带宽调谐机构

设计了一种由一直梁和两个半圆拱组成的开口环结构,并将均匀光纤布拉格光栅斜贴于直梁中间的表面处。对两半圆拱施加与直梁方向平行的应力作用时,光纤光栅受到线性应力场的作用,光纤布拉格光栅即转化为啁啾光纤光栅。该机构实现了光纤光栅带宽的线性调谐,线性度高达0．9982,实验结果与理论分析一致。与以往的带宽调谐机构相比,该机构具有很高的应力灵敏度,在20N力的作用下,可产生约7nm的带宽反射,灵敏度达0．34nm／N。利用环境温度对带宽调谐无影响的特性,采用带宽编码技术,研制出具有温度自动补偿特性、高灵敏度的带宽调谐装置。     

Mode-locked performance of hybrid soliton pulse source utilizing fiber grating external cavity lasers

Mode-locking characteristic of hybrid soliton pulse source (HSPS) utilizing linearly chirped raised-cosine flat top apodized fiber Bragg grating (FBG) is investigated by using coupled-mode equations. It is found that the fundamental repetition frequency range of HSPS is significantly extended by using linearly chirped raised-cosine flat top apodized FBG instead of linearly chirped Gaussian apodized FBG. The range of repetition frequencies over which proper mode-locking is obtained is 2-3.3 GHz with linearly chirped raised-cosine flat top apodized grating whereas this range is 2.1-2.95 GHz with linearly chirped Gaussian apodized grating.     

16×10Gb/s啁啾光纤光栅色散补偿系统性能研究

运用啁啾光纤光栅法对在G.652光纤传输的16×10 Gb/s信号实现色散补偿数值模拟和研究,分析了入纤光功率、色散斜率以及啁啾光纤光栅色散补偿带宽对系统误码率的影响,结论是:入纤光功率在8～16 dBm之间时系统的性能较好;啁啾光纤光栅的色散补偿带宽对系统的影响较大;光纤的色散斜率对系统误码率有一定的影响.     

Analytical investigation of response of birefringent fiber Bragg grating sensors in distributed monitoring system based on optical frequency domain reflectometry

When Fiber Bragg gratings (FBGs) are used as strain sensors, both longitudinal and lateral strain can be applied uniformly or non-uniformly over the length of the FBGs. In order for the demodulation of such FBG signal, this paper investigates the response of birefringent FBGs which are monitored by distributed measurement system based on optical frequency domain reflectometry. A numerical model of the distributed measurement system is built based on piece-wise uniform approach, which considers polarization states of propagating lights. The numerical model simulates analytical response of birefringent FBGs especially when birefringence induces power fluctuations in the distributed spectra, which can be noise or new opportunity for sensitive monitoring of birefringence. Simulation results show the relationships between the power fluctuations and the polarization states of the propagating lights. Consequently, appropriate methods of polarization control for sensitive distributed birefringent FBG monitoring are discussed.     

Performance limitation of chirped-fiber-Bragg-grating-based photonic microwave notch filter due to group delay and reflectivity ripples

We investigated the performance limitation of a frequency-tunable photonic microwave notch filter incorporating a chirped fiber Bragg grating (FBG) as a group delay line. In particular, we carried out theoretical and experimental studies to analyze the impact of the reflectivity ripple (RR) and group delay ripple (GDR) in the chirped FBG on the output notch performance. The results of experimental and theoretical analyses performed on a photonic microwave notch filter in which an S-bending-based linearly chirped FBG was incorporated, revealed that the notch depth and notch frequency were significantly affected by imperfections in the chirped FBG. The notch depth was found to be decreased by the RRs, whereas significant fluctuations in the notch frequency were caused by the GDRs. On the basis of the obtained results, we conclude that the RR and the GDR are the fundamental factors that degrade the performance of chirped FBG-based photonic microwave filters.     

A simple temperature-insensitive fiber Bragg grating displacement sensor

The study on fiber Bragg grating (FBG) displacement sensor based on monitoring the back-reflected power from an array of novelly embedded FBG sensors is presented. The sensor is a uniform FBG with three sections that are embedded in different layer in a composite lamina. Its bandwidth is displacement dependent and hence its reflected power varies almost linearly with displacement and it is insensitive to temperature variation. Thus, only low-cost photodetector (PD) is required to monitor displacement. This study demonstrates a novel fiber sensor, a method of fabricated the same, and a method to achieve simultaneous multi-sensor measurement.     

简支梁调谐啁啾光纤光栅的实验研究

利用有机玻璃块和螺旋测微器组成的简支梁系统调谐线性啁啾光纤光栅,将中心波长为1548.6nm、3dB带宽为0.43nm、长为25mm的均匀Bragg光纤光栅按一定角度牢牢的固定在一块长为90mm,宽为10mm,高为5.2mm的有机玻璃块中,再用螺旋测微仪在有机玻璃的中心位置向下施加压力,使简支梁及其中的光纤光栅变形,成为可调谐的啁啾光纤光栅。实验结果表明啁啾光纤光栅反射谱宽与简支梁弯曲量成线性关系,当简支梁最大弯曲量为1.2mm时光纤光栅反射谱展宽了4.02nm,而反射中心波长基本不变,该实验装置可以用于光控相控阵雷达天线的实时延迟线和光纤色散补偿。     

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.     

Small signal intensity modulation of external cavity lasers with fiber Bragg gratings

The small signal intensity modulation (IM) of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating (FBG) is described using electric field approach. The HSPS is modeled by a time-domain solution of the coupled-mode equations. It is shown that type of external cavity is important effect on resonance peak spectral splitting (RPSS) in IM response as well as effect of laser and FBG parameters. It is also shown that the RPSS can be suppressed by using linearly chirped Gaussian apodized FBG as an external cavity insted of Gaussian apodized FBG.