用显微干涉法测量光纤预制棒的折射率分布

一、引言截面折射率分布是优质光纤材料制备工艺中必须控制的一个最重要的参数,它对于所拉制成光纤的光传输性能有决定性的影响。因此,国内外的许多科技工作者在截面折射率测量方面做了大量的工作。根据所使用方法的原理,大体可分为:反射法、近场图象法、散射法和干涉法等四类。我们使用的方法属于显微干涉法的一种。干涉法无论在原理上或在方法上都比较成熟,所使用的设备较少,准确度和精确度也比较高。但是,它要求样品的两面具有高度     

分布光纤Raman光子传感器系统的优化设计

本文从新的解调方法、ＬＤ激光波长选择、光纤取样环修正方法出发,分析讨论了系统的优化设计。取得的主要实验结果如下：测温范围０￣１２０℃;测温不确定度±２℃;温度分辨率０．１℃;光纤绕组探头的空间分辨率〈５ｃｍ,在２ｋｍ光纤上可采样１０００个点。     

光纤CATV用实用化掺铒光纤放大器

本文从速率方程出发 ,利用 EDFA的大信号理论 ,采用加速迭代敛算法 ,对 EDFA进行了优化设计。在理论分析的基础上 ,设计出 CATV用 EDFA。经测试 ,各项性能参数达到较高要求。按此设计生产出的 EDFA已批量供应市场。     

用Raman光谱研究掺氧多晶硅的微结构

本文用Raman谱特征和Raman峰强度的变化,揭示掺氧多晶硅(SIPOS)的微结构:对于各种氧含量(从8％到38％)的SIPOS生长膜是一种无序结构,其中元素Si呈无定形相.高温(T>900℃)热退火后,薄膜经历了一个再结晶过程,并出现了微晶区,Si微晶尺寸随退火温度的提高而增大.膜中氧浓度增加对微晶生长有抑制作用,故膜中氧含量增加将使Si晶粒度减小,或者相应的使薄膜再结晶的温度提高.     

光纤陀螺用掺铒超荧光光纤光源

简要介绍了掺铒超荧光光纤光源的工作原理、基本结构.研制了一种采用单程后向结构、以980 nm激光二极管作泵浦源的小体积掺铒光纤光源.其输出功率大于5 mW,中心波长为1 544 nm,光谱3 dB带宽为41 nm,光谱平坦度小于等于±1 dB.     

塑料光纤预制棒折射率分布的测量

针对界面凝胶法制作的梯度折射率塑料光纤预制棒，提出了一种利用预制棒成像测量其折射率分布的方法，它是一种非破坏性测量。实验结果表明这种测量方法简单有效。     

光纤CATV用掺铒光纤大器的简化分析

在不考虑放大自发辐射（ASE）对掺饵光纤放大器（EDFA）饱和特性影响的条件下,推出了掺饵光纤放大器（EDFA）三能级系统功率传输的解析表达式,简化了理论分析,所得结果也适用于二能级系统。根据该简化分析方法具有计算了前向泵浦时光纤CATV用掺饵光纤放大器（EDFA）的信号增益曲线。计算表明,当信号增益约在25dB以下,即在光纤CATV用掺饵光纤放大器（EDFA）的工作范围内,简化分析所得的计算结果与较精确的数值计算结果一致。     

光纤CATV用掺铒光纤放大器的简化分析

在不考虑放大自发辐射(ASE)对掺铒光纤放大器(EDn)饱和特性影响的条件下,推出了掺铒光纤放大器(EDFA)三能级系统功率传输的解析表达式,简化了理论分析,所得结果也适用于二能级系统.根据该简化分析方法具体计算了前向泵浦时光纤CATV用掺铒光纤放大器(ED队)的信号增益曲线.计算表明,当信号增益约在25db以下,即在光纤CATV用掺铒光纤放大器(EDFA)的工作范围内,简化分析所得的计算结果与较精确的数值计算结果一致.     

光纤预制棒折射率分布的自动化测量

本文采用聚焦法,利用数字式选行器和采样保持器降低数据传输率,将光功率分布以电视视频信号的形式输入微型计算机,实现了预制棒折射率分布的自动化测量。     

掺镱光纤激光器粒子数空间分布研究

针对基于重叠因子模型的速率方程不能分析粒子数空间分布的情况,依据双包层掺Yb3＋光纤激光器中,内包层光强近似于均匀分布、而纤芯中光场近似于高斯分布的特点,建立了基于光强分布的速率方程。依据该方程,分析了正向、反向和双向泵浦方式下,Yb3＋上能级粒子数的空间分布。结果表明：沿光纤轴向,不同的泵浦方式导致上能级粒子数呈现不同的分布特征;而沿光纤径向,无论采用何种泵浦方式,上能级粒子数都呈现中间低、两端高的抛物线分布结构。     

大数值孔径光纤预制件研制

我们用MCVD法研制出GeO2—P2O5-SiO2系为芯，B2O3—SiO2系作也层的大数值孔径光纤，分近似突变型及渐变型折射率分布两种，NA=0．36，损耗=8dB／kM（在0．85μm长）。研究了GeO2-P2O5-SiO2系芯成分与相对折射率差△和损耗特性关系。消除了芯中心折射率凹陷。实验解决了预制件芯部的炸裂问题。     

乙基苯液芯光纤中受激喇曼散射产生超宽连续谱光源

本文使用乙基苯液芯光纤,获得高阶斯托克斯线,各阶线呈以红移为主的反常加宽。加宽后从一阶斯托克斯线至五阶斯托克斯线光谱联成一片,形成从562.1nm至700nm的连续超宽的相干辐射。     

Laser-drilled free-form silica fiber preforms for microstructured optical fibers

We describe a laser drilling technology suitable for structuring solid glass preforms for microstructured optical fibers. This technology offers the possibility to prepare complex preform designs that cannot be easily managed by the stack-and-draw technology. As a proof of concept, we present a four-ring hexagonal hole structure drilled in a silica rod over a length of 80 mm. A fiber drawn from such a preform has been analyzed to demonstrate the feasibility of this concept.     

Nondestructive measurement for arbitrary RIP distribution of optical fiber preforms

A nondestructive method is presented to determine simultaneously the refractive index profile and the cross section geometry of optical fiber preforms. An improved formula for calculating the optical path length from the deflection function is derived. The preform is rotated through 180/spl deg/ and the deflection angle data collected, then the back projection technique and linear interpolation algorithm are used in the computed tomographic two-dimensional (2-D) profile reconstruction for preforms of nonuniform cross section. To minimize the computing time, the spatial Nyquist frequency is analytically used to estimate the angle sampling number of views and the numbers of points per scan in advance. Numerical simulations and experimental results show that using 180/spl deg/ angle of view deflection data, accurate preform index distribution reconstructions are obtained.     

Raman spectra of hydrogen-treated optical fibres

Chemical reactions in a Ge-P-silicate optical fibre exposed to hydrogen at 100 bar and 150°C for times up to 120 h are studied by Raman spectroscopy. Hydride and hydroxyl groups are formed, as Si-H and P-OH. The reaction kinetics are consistent with a defect-related mechanism. The saturation concentration of hydroxyl is about 103 ppm.     

Raman amplifier model in single-mode optical fiber

Equations to describe the process of Raman amplification in single-mode optical fiber and Stokes and anti-Stokes spontaneous emission generation with conservation of photon number are derived from first principles. The numerical simulation of Stokes and anti-Stokes spontaneous emission is in good agreement with experimental results. The importance of the sometimes-omitted anti-Stokes spontaneous emission terms in wavelength-division-multiplexed situations for optical signal-to-noise ratio is demonstrated by the simulation of light propagation through transmission fiber with and without Raman amplification.     

Raman fiber oscillator as optical amplifier

A Raman fiber oscillator used for optical amplification is demonstrated to have lower double Rayleigh scattering, transient spikes, cross-phase modulation, and higher saturation input threshold compared with a conventional discrete Raman amplifier at similar operating conditions. This could be a promising technology for deployment in practical systems.     

The influence of codopants and fabrication conditions on germaniumdefects in optical fiber preforms

The GeE' defect concentration in MCVD germanosilicate preforms, as measured by cathodoluminescence profiles, is dramatically reduced by the addition of phosphorus as a codopant. The GeE' concentration is increased by using higher deposition temperatures and oxygen deficient conditions     

光纤共振喇曼光谱法探测水中超痕量生物分子

水中微量生物分子的探测、识别和控制研究是很重要的课题。采用光纤内共振喇曼光谱法,可以提高喇曼光谱的强度109倍。把少量β胡萝卜素溶于吡啶与水的混合液体,充入空心光纤中构成液芯光纤,用514.5nm,30mW激光激发,获得了浓度为10-7mol/L～10-9mol/L的β胡萝卜素喇曼光谱。该技术为研究水中微量生物分子提供了一种新的实验方法。     

Raman fiber lasers for optical communication application

We review the principle and characteristics of cascaded Raman fiber lasers in their telecommunication applications. The fundamentals of Raman fiber lasers are described, such as pumping scheme, fiber type and reflectors. We explain simple equations forcw laser operation as well as a possible way to calculate spectral width. We investigate the common issues in the use of Raman fiber lasers: theoretical optimization, control of the linewidth, suppression level of the other Stokes orders and relative intensity noise. Finally the more complex multiple-wavelength Raman fiber lasers are reviewed.