基于低增益低噪声光纤腔衰荡技术的湿度测量方法

提出了一种基于腔内带有低增益低噪声掺铒光纤放大器的光纤环形腔衰荡光谱技术测量湿度的方法,并进行了实验证明.比较分析了光纤环形腔中有无掺铒光纤放大器对衰荡脉冲数量的影响.在掺铒光纤放大器中使用长度为2m的低增益和低噪声掺铒光纤来减少波形失真并补偿腔内噪声衰减.利用光纤环腔衰荡光谱技术对空气相对湿度进行测量,记录分析环形腔中光脉冲的衰减时间τ得到相对湿度的变化.结果表明:相对湿度和衰减时间τ在相对湿度30%~100%的范围内满足良好的线性关系,并且光纤环腔衰荡系统的灵敏度和线性拟合度分别为3.826 79μs/RH和0.994 77.采用腔内带有低增益低噪声掺铒光纤放大器的光纤腔衰荡技术在工业检测、环境检测以及医学诊断等领域进行湿度测量将具有良好的应用前景.     

基于光纤环形腔衰荡光谱的偏振测量

针对传统偏振测量较难同时实现高灵敏度和较好稳定性的问题,提出了一种采用光纤环形腔衰荡光谱技术进行偏振测量的方法,并进行了实验证明.对比分析了掺铒光纤放大器放置在环形腔的内部和外部对脉冲曲线和脉冲数量的影响.在掺铒光纤放大器中使用长度为2m的低增益和低噪声掺铒光纤来减少波形失真并补偿环形腔的内部衰减.利用光纤环形腔衰荡光谱系统对偏振角进行测量,通过记录分析环形腔中光脉冲的衰减时间得到偏振角的变化.结果表明:偏振角和衰减时间在0°~90°的范围内满足良好的线性关系,光纤环形腔衰荡光谱系统的灵敏度和拟合曲线的相关系数分别为4.05μs/°和0.999 6,最大灵敏度误差为0.027 3μs/°.通过10次重复实验,选取六组数据进行拟合得到系统的平均再现性误差为0.030 8,重复性良好,可用于旋光溶液测量,也为光纤径向应力双折射特性和光纤激光器的偏振态测量提供了参考.     

铒镱共掺光纤放大器的高温老化输出功率

对1550 nm铒镱共掺光纤放大器不同温度下的输出功率以及经过高温老化后的输出功率和光谱进行了实验研究.通过对比高温和常温下铒镱共掺光纤放大器的输出功率随泵浦功率的变化曲线,得出铒镱共掺光纤放大器在高温环境工作可提高输出功率,且不同长度的增益光纤对温度的敏感性不同的结论.以Arrhenius模型为加速老化模型对增益光纤...     

L波段掺铒光纤放大器的自发辐射谱与增益的研究

利用Giles模型对L波段掺铒光纤放大器小信号增益特性进行了数值模拟,模拟结果表明最佳铒纤长度并不是一定值,它随输入信号波长的不同而改变,较短的波长对应较短的光纤长度;在数值模拟、分析的基础上,分别采用7m和9m的L波段铒光纤构成长波段掺铒光纤放大器,通过实验测量,分析比较了它们的自发辐射谱以及增益和噪声指数,得到了光纤长度对L波段增益谱、噪声指数和自发辐射谱的影响规律;最后,辅以C波段掺铒光纤放大器加以分析,指出了适合于放大L波段信号的最佳自发辐射谱型。     

长波段掺铒光纤放大器用掺铒光纤的设计考虑

本文分析了长波段掺铒光纤放大器(EDFA)的增益系数与Er³⁺离子浓度的关系.研制了铝共掺杂的高浓度掺铒光纤,以缩短长波段掺铒光纤的长度.用两级泵浦实现了L-波段EDFA.光纤放大器的掺铒光纤总长18m,在1570nm波长处的小信号增益为42.26dB,输出功率为17.5dBm.我们认为,较低的浓度淬灭效应归因于光纤中较高的A1掺杂浓度.当总的输入信号功率为-3dBm时,在1570至1600nm间的7路WDM信号的增益不平坦度仅为0.68dB..     

掺铒光纤放大器的优化设计

本文对掺铒光纤放大器优化设计方面的一系列问题进行了理论分析,通过对四十六所提供的掺铒光纤吸收谱的分析,分别计算了在掺铒光纤长度不同及入纤的泵浦功率不同的情况下,最佳的泵浦波长,理论分析了在不同的掺铒半径比的情况下的最佳截止波长,以及在不同的掺铒半径比和不同的掺杂浓度下的最佳掺铒光纤长度.     

有源循环式光脉冲复制系统的输出特性研究

改进并验证了一种基于有源循环光纤延迟线的模拟光脉冲信号复制技术.实验系统采用低增益掺铒光纤放大器补偿循环损耗.进行了光脉冲信号复制的仿真和实验,在掺铒光纤放大器增益为6.774 dB,光滤波器－3 dB,带宽为0.8 nm时,测得第500个复制光脉冲的信噪比为31 dB.仿真和实验结果表明,选用小增益掺铒光纤放大器可以实现低于3 dB的噪音系数,降低掺铒光纤放大器的放大自发辐射噪音并提高输出脉冲序列的信噪比,有望成为提高光脉冲复制器性能的一种新方法.在系统中插入窄带光滤波器等手段也是改善信噪比的有效措施.     

基于光腔环路衰荡光谱技术气体浓度测量的研究

为了实现痕量气体在线测量与分析,设计了光纤环路光腔衰荡多组分气体浓度在线测量系统;基于非线性光腔衰荡技术,利用所设计的系统对气体浓度在线测量并进行了实验分析;得出了同种气体不同浓度时光的吸收程度随时间变化的规律和1 ppb的分辨率.实验表明该方法对痕量气体的在线测量是有效的.     

掺铒孔辅助导光光纤的特性研究与优化设计

掺铒孔辅助导光光纤是由掺铒的高折射率纤芯、低折射率包层和少量的空气孔组成. 采用有限元法分析了掺铒孔辅助导光光纤的模式特性；给出了数值计算截止波长和模场直径的方法；提出了改进的平均粒子数反转度迭代算法来数值计算掺铒光纤放大器的增益和噪声系数. 研究空气孔对掺铒孔辅助导光光纤的截止波长、模场直径和放大器的增益系数的影响. 发现：减小相对孔芯距的值，可使截止波长向短波长移动，减小模场直径的值；当孔的相对大小较大时，截止波长、模场直径和增益的最大值基本上不随孔的相对大小的增大而改变. 最后，综合考虑掺铒光纤基模和二阶模的截止波长、与普通单模光纤的熔接损耗、放大器的增益和噪声系数等因素，优化设计了掺铒孔辅助导光光纤的四个结构参量——纤芯半径、纤芯与包层的折射率差、相对孔芯距和孔的相对大小. 关键词： 孔辅助导光光纤 掺铒光纤 光纤放大器 有限元法     

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.     

基于环形芯光纤的超低差分模式增益涡旋光纤放大器

提出了一种基于环形芯铒离子部分掺杂光纤的涡旋光纤放大器。针对该掺铒光纤的放大特性,研究了光纤长度、掺铒浓度与抽运功率对信号模式增益特性的影响。研究结果表明,该光纤放大器能够支持22个轨道角动量模式稳定传输,且C波段(1530~1565 nm)所有信号模式增益大于23 dB,信噪比高于27 dB,差分模式增益小于0.015 dB。所提出的基于环形芯光纤的涡旋光纤放大器具有支持轨道角动量模式数量多、差分模式增益低、信噪比高的优势,对于OAM复用长距离传输系统中的在线放大具有重要参考价值。     

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。     

A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber(HBEDF) as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm.At the optimum length of 0.5 m, the HBEDF amplifier(HBEDFA) achieves a flat gain of 26 d B with a gain variation of less than 1.5 d B within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at-30 d Bm and 140 m W, respectively. On the other hand, at the input signal power of-10 d Bm,the HBEDFA also achieves a flat gain of 14.2 d B with a gain variation of less than 2.5 d B within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier,the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of-30 d Bm, the gain improvements of 6.2 d B and 4.8 d B are obtained at 1525 nm and 1540 nm, respectively.     

高浓度镱铒共掺磷酸盐光纤放大器增益特性

在忽略高能级的自发辐射和光纤损耗的情况下，利用速率方程和传输方程理论研究了高浓度Er³⁺/Yb³⁺共掺磷酸盐玻璃光纤放大器的增益特性，讨论了Er³⁺浓度、Yb³⁺浓度、抽运光功率、信号光功率、光纤长度对放大器增益的影响，并与单掺铒光纤放大器进行了比较.由于Yb³⁺的敏化作用降低了铒离子的团簇效应，减少了离子间相互作用，共掺光纤的增益和效率明显高于单掺光纤.数值计算表明，3.2cm长Er³⁺/Yb³⁺共掺光纤在980nm的20dBm(100mW)抽运功率下，1532nm处的增益可达10dB. 关键词： 镱铒共掺光纤放大器 速率方程 传输方程 高浓度     

Simulation and experimental characterization of Raman/EDFA hybrid amplifier with enhanced performance

We present simulation and experimental characterization of a hybrid amplifier comprising of a Raman amplifier and an erbium doped fiber (EDF) amplifier, with enhanced performance. The incorporation of a pumped EDF section in a fiber Raman amplifier (FRA) employing a dispersion compensating fiber is demonstrated to provide superior performance than a sole FRA system. The hybrid amplifier is characterized in terms of single channel gain and noise figure, and the results of measurements are shown to be in close agreement with the simulated results. Polarization-dependent gain (PDG) and multi-channel measured and simulated gain characterization of the Raman/EDFA hybrid amplifier are also presented.     

A theoretical analysis of the effects of erbium ion pair on the dynamics of an optical gain stabilized fiber amplifier

In this paper, the effects of ion-pair formation on the gain dynamics of multi cavity optical automatic gain control erbium doped fiber amplifier is modelled. The inhomogeneous Cabezas simple model is used to write the rate and propagation equations for the active medium. The solution of the governing equations shows that in high concentration of the erbium ions, depending on the pumping rate, the relaxation oscillations are converted to nT-Periodic or even to chaotic behavior. Although the high concentration erbium ion in the optical amplifiers decreases the conversion efficiency and increases the threshold pump power, amplitude of the transient effects is reduced in the multi feedback-loop WDM amplifiers relative to the low concentration erbium ions multi feedback-loop optical amplifiers and ion-pairs, which act as a saturable absorber to compensate the gain tilt caused by the OAGC laser spectral hole burning. The theoretical results are in complete agreement with the previous published experimental results.     

铒离子与其它稀土离子共掺杂特性研究

掺铒光纤放大器设计应用于多波段放大,铒离子与其它稀土离子共掺杂所特有的宽吸收谱特性,使其在高功率放大器和高功率激光器的应用中得天独厚。为得到更宽放大带宽,最主要的是改变掺杂光纤的光谱性能。本文涉及的铒与镱、铥以及镧共掺杂光纤是采用MCVD工艺制备的,主要研究了离子浓度和掺杂比例对光纤光谱性能的影响。发现EDF的吸收与铒离子掺杂浓度以及铒离子与其它稀土离子的掺杂比例有关,同时通过加入其它稀土离子可以加宽EDF的吸收带。     

A global design of an erbium-doped fiber and an erbium-doped fiber amplifier

A global design of an erbium-doped fiber and an open-loop erbium-doped fiber amplifier (EDFA) in a steady-state operation is discussed by applying genetic algorithms. Taking a signal gain and a bandwidth as objective functions, 7 parameters of the EDFA (erbium concentration, core radius, erbium-doped radius, refractive index difference, fiber length, pumping wavelength and signal power) are optimized by solving optical propagation equations, assuming a homogenous two-level active medium and a single-mode propagation. There is evidence to show that the 1480 nm pump utilized in usual EDFAs is not an optimal choice, which should be chosen around 1460 nm. The optimal core radius ranges 0.465–0.548 μm on pumping power 50–200 mW. Under different design objects and with different pumping powers, however, there are different optimal Er-doped concentrations, reflective index differences and fiber lengths. As a single fiber EDFA, 35 dB signal gain or 35 nm bandwidth is obtained with the 7 optimal parameters, 100 mW pumping power and 0.001 mW input signal power.     

Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.     

Optimization of gain flattened C-band EDFA using macro-bending

Optimization of gain flattened C-band erbium-doped fiber amplifier (EDFA) using a macrobending method with an improved gain flatness and bandwidth is demonstrated. The optimization for gain flatness and bandwidth was achieved by varying the bending radius and the length of the doped fiber. In the optimized condition, the gain saturation effect as well as the energy transfer from shorter wavelengths to longer wavelengths resulted in a flattened and broadened gain profile in the C-band region. The amplifier was optimized to a 9 m long erbium-doped fiber (EDF) with erbium ion concentration of 1100 ppm and bending radius of 6.5 mm. The gain variation of the EDFA is obtained within ±1 dB over 25 nm bandwidth of C-band region.