聚合物光纤热预拉锥工艺实验研究

文中研究了重力垂直熔融拉锥法中不同温度、不同拉伸力工艺条件对聚合物光纤热预 拉锥特性的影响。实验表明:加热区中心温度为214℃附近和拉伸力为1. 40g左右时, PMMA聚合物光纤拉伸过程容易控制,并且具有良好的光学质量。     

熔锥型光纤耦合器的工艺与显微形貌研究

以六轴光纤耦合机为实验平台,研究了熔融拉锥光纤耦合器的工艺、性能、显微形貌三者之间的相关规律.利用热电偶和电位差计测得了熔融拉锥时火焰的温度场分布,利用扫描电子显微镜观察了光纤耦合器的显微形貌.经大量观测实验研究发现:在光纤耦合器的锥形区域,存在皲裂,并且拉伸速度越快,皲裂越明显;在光纤耦合器的耦合区域,光纤表面存在微小晶粒,而内部没有发现微晶,即光纤耦合器玻璃表面发生了析晶现象,且拉伸速度越慢,晶粒越大.     

熔融光纤拉锥动态形状函数的理论与实验研究

导出了熔融光纤拉伸锥体动态形状曲线的数理方程,结合初始边界及体积守恒条件获得方程显解.这种解析解对于任意参数的灯头、能方便、精确和完整描述熔融光纤在不同拉锥过程中锥体动态形状的变化,从而能精确描述各种熔融光纤器件拉伸时的动态耦合过程,理论分析与实验结果非常吻合.研究结果表明,只要测出初始熔融区长度,获得的理论解就能预知任意拉伸长度下的拉锥锥形曲线.     

二氧化碳激光熔融拉锥系统

为了更精确地控制光纤熔融拉锥过程,利用二氧化碳激光器和自主设计改造的时间控制模块、光纤牵引模块搭建了二氧化碳激光熔融拉锥系统。在该系统中,设计时间控制模块对二氧化碳激光器的出光时间进行严格控制,找到单脉冲和多脉冲模式下的最佳功率参数和最佳时间参数,找到最佳热熔效果参数。搭建的二氧化碳激光熔融拉锥系统操作简单,可以提高熔锥型器件的精度。     

熔锥型光纤耦合器的制备与测试

论述了熔锥型光纤耦合器的功率耦合理论，利用熔融拉锥法制得了3dB单模光纤耦合器。利用可调谐光源和光谱分析仪组成的光学测试系统，测试了熔锥型光纤耦合器的附加损耗、方向性与均匀性等光学性能。实验表明，该方法具有制作简单、较低的附加损耗和良好的方向性等优点。利用扫描电子显微镜观察了光纤耦合器的表面，发现在光纤耦合器的锥区存在微裂纹，并且拉伸速度越快，微裂纹越明显；在光纤耦合器的耦合区．光纤表面存在微小晶粒，且拉伸速度越慢，晶粒越粗大。     

拉锥光纤的制作工艺与测试方法

在分析移动火苗拉锥技术原理的基础上,对商用拉锥机参数进行了分析,并设计、制作了不同形状的拉锥光纤。为了检测制成的拉锥光纤实际形状与理论预测的符合度,设计了傅立叶光学衍射测量系统,对拉锥光纤样品测试,结果证明了理论分析方法的合理性。对固定火焰拉锥机,给出了控制拉伸距离得到特定形状拉锥光纤的方法。     

计算机控制的CO2激光熔融拉锥系统

针对现有熔融拉锥法(FBT)的缺陷,提出了一种CO2激光熔融拉锥系统。系统主要由CO2激光器、振镜和自动平移台三部分组成,通过计算机对其进行联合控制。试验结果表明利用该系统可精确控制熔锥光纤的形状,从而提高熔锥型器件的精度。     

熔融拉锥过程中熔锥形状特性的研究

为了便于精确控制熔锥光纤的形状,基于理论与实验研究,首先建立了熔融拉锥过程中熔锥光纤的成形模型,分析了熔锥形成的基本原理,并分别对加热区域不变及线性变化两种情况下熔锥形状进行理论分析,确定了加热区域长度、拉锥距离与熔锥过渡区形状、锥腰长度及半径的关系,最后给出了一系列熔锥光纤的理论形状和实验得到的实际形状。实验结果表明,熔锥的实际测量值与理论值十分接近,相对误差<3.89%。     

利用普通熔融拉锥机实现光子晶体光纤拉锥

光子晶体光纤的拉锥是实现光子晶体光纤潜在应用价值的重要技术手段。通过优化普通光纤拉锥机的参数,利用"快速低温"拉锥法有效控制了光子晶体光纤空气孔的相对塌缩。实验中实现了两种不同光子晶体光纤的拉锥,光纤外径分别从原来的125μm拉锥到50μm和30μm,光纤的孔直径和孔间距之比基本保持不变,拉锥损耗小于0.4 dB。基于普通熔融拉锥机的光子晶体光纤低损耗拉锥为光纤器件的制作奠定了基础。     

熔融拉锥技术在光纤耦合传输中的应用

为了实现光纤激光器和放大器系统中不同参量光纤的低损耦合,采用光纤拉锥方法来实现光纤连接。经过理论分析,在大数值孔径光纤传输到小数值孔径光纤时,采用光纤拉锥技术可以有效地提高传输功率。采用改造的大模光纤熔接机进行拉锥实验研究,精确控制拉锥时间、放电功率、步进量和步进速率可以获得不同的拉锥形状。采用光纤拉锥元件对标准单模光纤和大模场光纤进行耦合实验,得到纤芯内传输的耦合输出效率由之前的50%提高到85%,获得了低损连接效果。结果表明,熔融拉锥技术为不同光纤之间的耦合提供了一种简单实用的方式。     

The shape of fiber tapers

A model for the shape of optical fiber tapers, formed by stretching a fiber in a heat source of varying length, is presented. Simple assumptions avoid any need for the techniques of fluid mechanics. It is found that any decreasing shape of taper can be produced. The procedure for calculating the hot-zone length variation required to produce a given shape of taper is described, and is used to indicate how an optical adiabatic taper can be made. A traveling burner tapering system is capable of realizing the model's prediction, and a complete practical procedure for the formation of fiber tapers with any reasonable shape is thus presented     

Compact modal interferometer built with tapered microstructured optical fiber

A modal interferometer was built with tapered large-mode-area microstructured optical fiber (MOF). The tapering was introduced by slowly stretching the fiber while it was heated with a high temperature flame torch. With this "slow-and-hot" tapering process, the MOF air holes collapse and the taper waist is transformed into a solid unclad multimode fiber. This allows the coupling between the fundamental HE/sub 11/ MOF mode and the HE/sub 1m/ modes of the solid fiber. The beating of the HE/sub 1m/ modes makes the transmission spectra of the taper to exhibit an oscillatory pattern. The influence of the taper geometry and wavelength on the interference pattern is discussed. The interferometer can be used for diverse applications.     

Theoretical, Numerical, and Experimental Analysis of Optical Fiber Tapering

An optical fiber taper is fabricated by heating and stretching a fiber. The resulting taper shape is important as it strongly affects optical performance. In this paper, the tapering process of solid optical fiber is modeled and analyzed under several heating and stretching conditions. The fiber material is assumed to be of non-Newtonian inelastic type. The results show that for a given heating profile, the shape of a tapered fiber is independent of the material properties and the stretching conditions applied at the fiber ends, and a section of uniform waist can be formed as long as the extensional deformation rate in a section of the heating zone is position-independent. Different shapes of fiber tapers can only be achieved by using different heating profiles. Therefore, spatially uniform heating of the fiber within the heating zone is of critical importance for producing a taper with a uniform waist. This is particularly true if the fiber material has a low deformation temperature     

Novel Method for the Fabrication of Long Optical Fiber Tapers

We report a novel fiber taper facility that allows the fabrication of fiber tapers between a few centimeters and tens of meters in length and that can be used for standard and microstructured optical fibers (MOFs). Efficient reduction of error in diameter variation is achieved using the velocity control feedback loop. The experimental results of the tapering of both the step index fiber and the MOF are presented. The observed outer diameter tracking error over the taper length was within 1%.     

基于拉锥单模-多模-单模光纤结构的高灵敏折射率传感器

文章介绍基于拉锥单模-多模-单模(SMS)光纤结构的模间干涉仪,当拉伸长度为35mm时形成自由光谱区(FSR)为1.3nm的干涉透射谱,消光比达到10dB。此时拉锥多模光纤的腰椎平坦区直径约为3.85μm,具有较强的倏逝场,可用作高灵敏折射率传感器。实验证明,此拉锥SMS结构在折射率范围1.35-1.36内的灵敏度高达771nm/RIU,能精密监测溶液溶质扩散现象。     

球聚焦型3×1光纤熔锥耦合器的研究

以线性耦合波方程为基础,采用散射矩阵的方法讨论了等三角分布的熔锥型3×1光纤耦合器,并用射线理论分析了球聚焦透镜光纤的端面效应。将未封装的3×3熔锥光纤耦合器在束腰处切断,并将锥端面熔成聚焦球端,利用光信号在光纤锥形区和球聚焦透镜中特有的传输和耦合特性,实现了光纤的耦合、连接和分束。结果表明:采用该方法耦合效率可达70%左右。同时大大增加了耦合系统的失调容差,降低了调试和封装的难度,因而有着广泛的实际应用价值。