光纤激光的频谱组束技术

频谱组束具有结构简单、便于控制等特点,是实现大功率、高质量光纤激光输出的有效手段.介绍了利用光栅、变换透镜等元件进行光纤激光频谱组束的基本结构和原理.综述了光纤激光频谱组束技术的最新进展情况,包括MOPA结构的频谱组束、三光栅结构的频谱组束和基于PTR布拉格光栅的频谱组束;比较分析了各种组束方法的优缺点.分析了当前频谱组束技术要解决的关键问题并展望了其发展前景.     

光纤F-P腔压力传感器在高温油井下的应用研究

针对高温、高压油井的测量环境,设计研制了基于光纤非本征型Fabry-Perot(F-P)腔的波长解调型光纤压力传感器系统.该系统采用激光熔接制作的光纤F-P传感头,具有测量动态范围大、温度敏感性小、耐高温和长期工作稳定等优点,在压强0～30 MPa范围内,系统压力测量分辨率达到0.003 MPa,温度敏感性小于0.002 MPa/℃.光纤传感头采用光纤-厚壁石英管激光熔接的无胶封装方式,解决了高温环境下的传感器高压密封和光纤保护问题.     

一种闭环控制的光纤光栅动态色散补偿仪

利用啁啾光纤光栅的应变调谐特性，将色散补偿的啁啾光纤光栅斜贴于悬臂梁的侧面，通过应力实现啁啾量调整而改变其色散补偿量的大小，同时利用固定在同一悬臂梁的均匀布拉格光栅传感器，实现了闭环自动控制色散补偿量，研制出了一种新型的光纤光栅动态色散补偿仪。该色散补偿仪工作在1550nm波段，典型性能数据为：色散动态补偿范围-1000-1680ps／nm，插入损耗小于1．5dB，动态调谐步进响应时间小于50ms，基本上能满足10Gb／s光纤通信系统中色散动态补偿的要求。     

Postfabrication wavelength trimming of fiber Bragg gratings writtenin H2-loaded fibers

A postfabrication technique for writing fiber Bragg gratings in H ₂-loaded fiber with precise wavelength control is reported. The grating wavelength is highly stable and less than a 0.01-nm shift was observed after storing at room temperature for two months. This technique allows 1 nm of wavelength trimming and significantly enhances the grating thermal stability     

光纤光栅透射谱线的测量

在已有光纤光栅调谐技术的基础上,研究了一种由不同光谱特性的光纤光栅组成的光栅对,用于测量光纤光栅谱线结构。并给出了测试结果。     

Fiber Bragg grating (FBG) characterization and shaping by localpressure

The spatial distribution of the chirp profile of a 4-cm-long nonuniform fiber Bragg grating (FBG) was studied with the exertion of local pressure on the fiber through the application of transverse force to a small grating section (~0.3 mm). The technique was also used for spectrally shaping a previously unchirped, 18-cm-long Bragg grating, generating a narrow transmission window (~400 MHz) inside its reflective band. A physical model was developed in order to estimate the phase shifts induced by pressure. A numerical simulation based on the piecewise-uniform approach was also used to calculate the consequent changes in reflected spectrum. Experimental and theoretical data show good agreement and the pressure technique proved to be adequate for grating characterization and spectral shaping     

Strain-induced thermally tuned long-period fiber gratings fabricated on a periodically corrugated substrate

This paper reports the characteristics of a strain-induced thermally controlled loss-tunable long-period fiber grating (LPFG) fabricated on a prepatterned corrugated substrate. Periodic microbending at the fiber-substrate interface induces mode coupling between the core and asymmetrical cladding modes that yields narrow-band attenuation as large as -25 dB. Several parameters that affect the performance of the tunable LPFG, such as the diameter of the etched fiber, number of grating periods, curing condition, and thermal expansion properties of the bonding materials, are investigated. This paper also demonstrates the integration of an on-chip thin-film microheater that also functions as a temperature sensor for the LPFG.     

光纤光栅外腔半导体激光器频率调谐技术研究

在分析了光纤光栅外腔半导体激光器(FBG-ECL)基本特性的基础上,调研了适用于该类型激光器的频率调谐方法,包括温度调谐法和应力调谐法,选取轴向应力调谐法改变光纤光栅的布拉格中心波长,进而实现频率调谐。利用压电陶瓷(PZT)来对光纤光栅施加轴向应力,通过调整PZT驱动电压值的大小来控制光纤光栅布拉格中心波长的变化量。实验结果表明,对于波长1550 nm的光纤光栅激光器,当PZT的驱动电压增加到126 V时,可实现 0.8 nm,即100 GHz的调谐范围以及每周期2 ms的调谐速度。     

光纤Bragg光栅的电磁波理论及其数值分析

以电磁波耦合模理论为基础,在正向基模与反向包层模的耦合作用存在时,导出了光纤Bragg光栅的反射率、透射率的解析表达式.通过对相关理论结果的数值分析,研究了光纤Bragg光栅的光谱特性,表明了光栅参数以及包层模式对其光谱特性的影响.所得结果为光纤光栅器件的优化设计及其应用提供了理论基础.     

Wavelength-interleaved OADMs incorporating optimized multiple phase-shifted FBGs for fiber-radio systems

We demonstrate that a single fiber Bragg grating (FBG)-based optical add-drop multiplexer can be used to improve the optical spectral efficiency in a mm-wave WDM-fiber wireless network. The technique employs wavelength interleaving in conjunction with optical single-sideband modulation, together with a single multiphase-shifted fiber Bragg grating. Wavelength optical add-drop features are also demonstrated using the grating, and our results show the performance of the novel grating in terms of channel isolation and add-drop functionality. We perform simulations to optimize placement of the phase shifts when an apodization profile is applied to the grating, in an attempt to minimize in-band and out-of-band transmission-amplitude ripples. Experiments are performed using cascade configurations both with the apodized gratings with optimal phase-shift positions and with the original unoptimized gratings. The experimental results demonstrate how these novel gratings can be used in fiber-radio networks incorporating multiple optical add-drop multiplexers.     

光纤光栅外腔反馈的高功率半导体激光器光谱特性的研究

对光纤光栅外腔反馈的高功率半导体激光器的光谱线宽特性进行了理论与实验研究。理论分析表明，根据不同的外腔参数，激光器的线宽能被压缩或展宽。外腔反射率对光谱线宽的影响要比外腔腔长灵敏得多。实验实现了激光器的线宽由６ｎｍ到０．８ｎｍ的压缩。光纤光栅外腔反馈不仅能改善高功率半导体激光器的光谱特性，而且可提高激光器主模对次模的抑制比。     

长周期光纤光栅光谱响应与结构参数关系的研究

本文应用耦合模理论分析了长周期光栅的光谱特性。运用传输矩阵法模拟计算并分析了光栅结构,如折射率分布包格、平均折射率变化和啁啾系数的改变对长周期光栅光谱特性的影响,得到光谱响应规律,提供了长周期光纤光栅光谱特性设计的理论分析。     

长周期光纤光栅对结构参数的敏感特性

基于模式耦合理论,对影响长周期光纤光栅（LPFG）光谱特性的各种物理结构参数进行了研究,得到LPFG光谱特性响应的一系列定量或定性的规律。利用紫外线,通过振幅掩模法曝光H载掺Ge光纤制作了两根LPFG,写入的光栅长度分别为3.0 cm和4.5 cm,测得温度灵敏度分别为0.044 6 nm/℃和0.059 4 nm/℃...     

Monitoring diesel engine parameters based on FBG probe

This paper proposes an unprecedented systematic approach for real-time monitoring the temperature and flow of diesel engine by using embedded fiber Bragg grating (FBG). By virtue of FBG’s temperature effect, we design a novel sensitive FBG temperature sensing probe to measure the temperature of cylinder head and inlet flow of diesel engine. We also establish the corresponding software platform for intuitive data analysis. The experimental and complementary simulation results simultaneously demonstrate that the FBG-based optical fiber technique possesses extraordinary reproducibility and sensitivity, which makes it feasible to monitor the temperature and inlet flow of diesel engine. Our work can provide an effective way to evaluate the thermal load of cylinder head in diesel engine.     

啁啾长周期光纤光栅的滤波特性研究

基于光纤光栅耦合模理论,采用传输矩阵法对啁啾长周期光纤光栅的啁啾系数和光栅参量（光栅长度、光栅周期和折变量）对其滤波特性的影响进行分析。当啁啾系数处于-0.000008～-0.0004 nm/cm范围内时,可用于宽带带阻滤波器。当啁啾系数处于-0.05～-1 nm/cm范围内时,可用于多通道窄带滤波器。为啁啾光纤光栅滤波器的优化设计提供理论依据。     

具有光敏下陷包层的B/Ge共掺光敏光纤的研制

紫外光纤光栅的包层模造成的损耗限制了光栅在波分复用系统中的使用。文章分析了同时具有下降内包层和光敏内包层的光敏光纤可以极大地抑制包层模耦合,并采用ＭＣＶＤ工艺制作出硼和锗共掺（Ｂ／Ｇｅ）的带光敏的下陷内包层的光纤,经写入紫外光纤光栅证实该光敏光纤确实极大地抑制了包层模耦合。     

相移布喇格光栅滤波器的分析及其串扰对FDM－FSK光纤传输系统复用路数的影响

提出并分析了一种新型的布喇格光栅滤波器，用模式耦合方程分析了滤波器的传输特性，计算了通带宽度、自由谱宽和精细度。并把它用在以频移键控（ＦＳＫ）方式调制的频分复用系统中，得到了比较理想的结果。     

基于长信号快速相关算法的FBG传感解调

针射光纤布拉格光栅（FBG）复用传感解调技术中光纤上复用光栅的数量问题，基于F-P滤波器，提出用长信号快速相关算法来检测波长移位的解调方法。通过MATLAB仿真和具体实验证明：该方法在实际中可以解决两波形部分（〈40％）重叠的问题，进而在光谱宽度、测量范围和光栅谱宽一定的条件下，使复用光栅的数量大大增加，同时测量精度可达到1pm。     

Optical fiber recirculating delay line incorporating a fibergrating array

For a practical optical fiber recirculating delay line the maximum notch depth and tunable free spectral range are difficult to achieve because of fixed coupling coefficient and loop length. We present here an optical fiber recirculating delay line incorporating a fiber grating array. In this work, the effect of insertion loss in the delay loop is investigated and used to maximize the notch depth of the frequency response. The tunable free spectral range is obtained from the wavelength dependent loop length introduced by the fiber grating array