Practical barrier to hydrogen diffusion into optical fibres

The diffusion of hydrogen (at 65 atm) into optical fibres coated with silicon oxynitride is found to be several orders of magnitude lower than that for uncoated fibres. Extrapolation of the data using a diffusion model predicts that such coatings should provide a practical and effective barrier against lower hydrogen pressures over system lifetimes. Thus all hydrogen-related optical ageing effects are significantly reduced.     

Increased attenuation in optical fibres caused by diffusion of molecular hydrogen at room temperature

A new set of absorption peaks has been observed at wave-lengths between 1.5 and 2.5 ?m in silica-based optical fibres which have been exposed to hydrogen at room temperature. The largest peak, at 2.42 ?m, is identified as being due to the fundamental molecular hydrogen vibrational absorption. Other peaks in the set are related to the fundamental with the same energy shifts as previously reported for the first overtone spectrum. The implications of both sets of peaks are quantified for the operating windows of optical fibre systems at 1.3 and 1.55 ?m.     

Photobleaching effect on visible-region loss increase for heat-treated optical fibres in a hydrogen atmosphere

The photobleaching effect on the visible-region loss increase due to hydrogen was observed for the first time by argon-ion laser light launching in fibres. A 660 nm fluorescence intensity reduction for the bleached fibres was also observed.     

Loss spectra of optical fibres under hydrogen and deuterium

Assignment of the frequencies at the loss peaks due to hydrogen permeation is clarified on the basis of the loss spectra in silica glass fibre under deuterium. As a result, it is concluded that the loss peaks due to hydrogen permeation in silica glass fibre are related to the combinational vibrations of hydrogen molecular vibration and SiO4 tetrahedral vibrations.     

Effects of hydrogen diffusion on optical fibre loss increase

The time dependence of fibre loss increase due to hydrogen diffusion for different pressures and temperatures is reported. It is found that the optical fibre loss increases with increasing hydrogen pressure as well as temperature, and decreases with increasing temperature when removed from the hydrogen environment.     

Chemical change from diffused hydrogen gas to hydroxyl ion in silica glass optical fibres

The chemical change from hydrogen gas that diffuses into silica glass for optical fibres to hydroxyl function has been investigated. Hydrogen molecules that diffuse into GeO2-doped silica glass at 500°C easily change into OH ions by thermal energy, while this chemical change does not occur in pure silica glass at 500°C. Also, germanium-doped silica fibre, in which hydrogen gas is dissolved at room temperature, shows OH ion absorption loss increase with chemical change by heat treatment at above 100°C, while pure silica core fibre shows no OH ion absorption loss increase by the same treatment.     

Coloration and its reduction in phosphorus-doped low-loss optical fibres

Coloration and its reduction in phosphorus-doped low-loss optical fibres have been investigated. The absorption loss at 0.53?m is as high as 60 to 100 dB/km when measured immediately after the drawing process. The coloration, however, can be almost completely reduced by annealing at 100°C for 48 h.     

光纤Bragg光栅及其在光纤通信中的应用

本文对光纤光栅的光学特性和制造技术进行了介绍，并对其在制作高性能光纤器件方面的几种典型应用进行了评述     

Leaky rays on optical fibres of arbitrary (circularly symmetric) index profiles

The local plane-wave decomposition approach used to analyse optical fibres of arbitrary refractive-index profiles has been extended to include the case of so called `leaky? rays. The result thus obtained for acceptance angle represents a generalisation of results derived previously for simple forms of the profile by geometrical-optics methods.     

光纤Bragg光栅温度和应变的灵敏度分析及应用探讨

本文从Ｂｒａｇｇ光栅方程出发,推导出了光纤Ｂｒａｇｇ光栅传感器的温度和应变一阶和二阶灵敏度以及温度－应变交叉灵敏度的计算公式,结合实际数据进行了计算,估计了忽略二阶和交叉灵敏度可能带来的误差,并指出改变Ｂｒａｇｇ光栅的封装形式可以提高其温度灵敏度,用此方法同时测量温度和应变时,可以降低灵敏度矩阵的条件数,从而提高检测精度。     

GaAs膜内注入载流子感生的折射率相对变化谱及其对光开关特性的影响

实验测量了不掺杂GaAs膜内注入载流子感生的820～900nm波段反射率相对变化谱,从而得到对应的折射率相对变化谱,并分析其对光开关特性的影响。     

The effect of hydrogen on boron diffusion in SiO2

The diffusivity of boron in silicon dioxide may be increased by the introduction of hydrogen into the annealing atmosphere. In this paper we report on the diffusion characteristics of boron ion-implanted into thermally grown SiO₂. A sensitive technique was used in which the boron atoms redistributed into the substrate are characterized by electrical methods. The diffusivity of boron in thermal SiO₂ was measured over the temperature range of 950-1150°C with hydrogen partial pressure from 0 to 0.2 atm. It was found that the diffusion coefficient of boron in oxide at 1150° C increases as the square root of the hydrogen partial pressure. At fixed pressure the temperature dependence of the diffusion coefficient obeys a single-activation-energy exponential rule. At 0.1 atm partial pressure of H₂ the activation energy is 3.0 eV and the preexponential factor is 6 x 10⁵ [cm²/sec.].     

?-ray irradiation effect on transmission loss for ZrF4-based optical fibres

The ?-ray irradiation effect on the transmission loss of ZrF4-BAF2-GdF3-AlF3 and ZrF4-BaF2-GdF3-AlF3-PbF2 optical fibres is investigated. Absorption bands are induced in the ultraviolet to near infrared region, and their tails increase the transmission losses in the mid-infrared region. Induced transmission losses for a dose of 106 R are 1000?2300 dB/km in the 2?4 ?m band. These values are comparable to those at 1.5 ?m for doped silica fibres.     

单模光纤有效面积及其测试方法

有效面积（Aeff)是一个与光纤非线性密切相关的极其重要的参数,随着通信距离的延长和WDM通道的增加,人们对光纤Aeff的值越来越关心,如何准确方便地测量出Aeff值成了关注的问题,文章介绍了Aeff的概念,定义及其测试方法,并对几种测试方法特点进行了比较和分析。     

若干弱光非线性光学效应及其应用

简要介绍了弱光非线性光学领域中一些研究方向的进展,如弱光非线性光子学材料中的缺陷结构、介观量子相干系统中光传播动力学和慢光非线性光学等,着重描述了近期在新型激子与紫外弱光非线性光学效应、位相耦合与光速调控以及非相干空间孤子阵列诱导光学晶格与光非线性传输行为等研究中得到的研究结果。弱光非线性光学将成为非线性光学应用领域中的一个重要分支。     

Wavelength multiplexed hydrogen sensor based on palladium-coated fibre-taper and Bragg grating

A novel configuration of a wavelength multiplexed hydrogen sensor based on a palladium-coated tapered fibre and a fibre Bragg grating is presented. This scheme allows cascading several sensors along a single fibre, which increases the capability of implementing multipoint sensor networks for volumetric detection. Moreover, in this configuration the light interacts twice with the palladium layer, thus enhancing the sensitivity of the sensor.     

FBG的衍射光学特性和耦合模理论分析

从衍射光学的角度出发研究了光纤布喇格光栅（ Ｆ Ｂ Ｇ） 的光学特性,进而采用理想模展开的耦合模理论对光纤布喇格光栅的模场分布进行了详细分析,推导出反射率、布喇格反射波长及反射主峰带宽等特性参数的表达式。计算结果表明,理论与实验结果吻合较好,从而验证了理论结果的正确性     

The effects of drift and diffusion in semiconductors on plane waveinteraction at interfaces

The field solution for a semiconductor material is presented in terms of gradient and curl components based on a drift-diffusion model. This is done for both biased and unbiased semiconductors where the bias causes a drift current. A simple demonstration of the field representation is given for plane-wave scattering at a dielectric-semiconductor interface when the incident field used is either TM^z or TE^z     

光纤Bragg光栅流量传感器的研究及进展

光纤Bragg光栅流量传感器是基于光信号的新型流量传感器.当光纤光栅受到流体的作用时,其波长、相位都会发生变化,通过检测光信号的变化就可得到外界流量的变化.文章主要介绍了几种光纤光栅流量传感器的工作机理,分析了各种流量传感器的优缺点,并对光纤光栅流量传感器的发展进行了展望.