【作者】 郑凯；

【导师】 简水生；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2007， 博士

【摘要】 特种光纤及其相关器件在光通信、传感、材料加工和军事等领域有着广泛而重要的应用。本论文在国家高技术研究发展计划（863）项目“稀土掺杂光纤”和“新型特种光纤”的支持下，对掺铒保偏光纤、掺铒微结构光纤和长周期光纤光栅等进行了深入系统的研究，获得以下创新性成果：1．提出一种新型的制作熊猫型掺铒保偏光纤预制棒的方法—U型槽嵌入法，此方法制作工艺简单，易于操作，而且成品率高。采用新型石墨电炉加热的MCVD法结合溶液掺杂技术制作掺铒芯棒。2．综合考虑光纤的截止波长、模场直径、背景损耗和双折射等性能指标，优化设计了熊猫型掺铒保偏光纤的结构参量。据此优化参量，利用U型槽嵌入法试制出高吸收系数高双折射的熊猫型掺铒保偏光纤。所研制的纤芯共掺铋镓铝铒的保偏光纤在波长1530nm处的吸收系数高达58dB／m；外径为125μm的掺铒保偏光纤的双折射达到4.8×10^-4；在1200nm处的背景损耗小于15dB／km。3．给出了一种准确高效的模拟掺铒光纤放大器的算法—改进的平均粒子数反转度迭代算法；采用此算法结合有限元法研究了掺铒微结构光纤放大器的性能。利用有限元法数值分析了空气孔对掺铒微结构光纤的截止波长、重叠积分因子和模场直径的影响。综合考虑掺铒光纤的截止波长、放大器的增益系数和与普通单模光纤的熔接损耗等，优化设计了掺铒微结构光纤的结构参量，并与普通掺铒光纤的性能进行了比较。4．基于标量近似和耦合模理论系统深入地研究了振幅掩模紫外写入的长周期光纤光栅的特性。理论推导出辐射模的归一化系数和长周期光栅中纤芯模与辐射模之间的耦合方程。数值分析了纤芯模与辐射模之间耦合系数的特性，并给出了数值估计外部环境折射率高于石英包层折射率时长周期光栅的谐振波长的方法。利用有限元法结合耦合模理论研究了各结构参量对基于孔辅助导光光纤的长周期光栅的谐振波长和耦合系数的影响。更多还原

【Abstract】 Special optical fibers and related devices have great applications in the optical communications, sensing, material process and military fields. In this dissertation, we concentrate on the study of the erbium-doped polarization-maintaining fibers （EDPMF）, erbium-doped microstructured fibers and long-period fiber gratings. And the work is supported by the National High Technology Research and Development Programs of China, "Rare-earth doped fibers" and "Novel special optical fibers". The main achievements of this dissertation are listed as follows:1. A novel method called the U-shaped groove method is proposed for fabricating the Panda-type erbium-doped polarization-maintaining fiber preforms. This method is easy to operate and can increase the yield. And the erbium-doped optical fiber preforms are fabricated by the combination of the Furnace-MCVD process and the solution doping technique.2. The structural parameters of the Panda-type EDPMFs are optimized in terms of the design criteria, which take into account the EDPMFs’ cutoff wavelengths, mode field diameters, background loss and birefringence. High absorption and high birefringence Panda-type EDPMFs are successfully fabricated by the U-shaped groove method. The absorption coefficient of the EDPMF, whose core is co-doped with Bi, Ga A1 and Er, is about 58dB/m at the wavelength of 1530nm. The birefringence of the EDPMF, whose outer cladding diameter is 125μm, is about 4.8x10^-4. And the background loss is less than 15dB/km at the wavelength of 1200 nm.3. The modified average population inversion iteration method is proposed for calculating the gain and noise figures of erbium-doped fiber amplifiers. The characteristics of erbium-doped microstructured fiber amplifiers are investigated by the combination of the finite element method and the modified average population inversion iteration method. The effects of air holes on the cutoff wavelengths, overlap factors and mode field diameters of the erbium-doped microstructured fibers are analyzed by using the finite element method. The structural parameters of erbium-doped microstructured fibers are optimized in terms of the design criteria, which take into account the cutoff wavelengths, the gain and noise figure of fiber amplifiers and the splice loss between the erbium-doped microstructured fiber and the conventional single-mode fiber. The comparison between the erbium-doped microstructured fiber and the conventional erbium-doped fiber is made.4. The characteristics of the long period fiber gratings, which are ultraviolet-written by the amplitude mask, are studied in detail by using the scalar approximate and coupled-mode theory. The normalization of the individual radiation mode is discussed and the coupled equations between the core mode and radiation modes are deduced. The properties of the coupling constants between the core mode and radiation modes are investigated. The numerical calculation of the resonance wavelengths of the long period fiber gratings is given, when the refractive index of ambient environment is higher than that of silica cladding. The effects of the structural parameters on the resonance wavelengths and the coupling constants of the long period fiber gratings based on the hole-assisted lightguide fibers, are studied by the combination of the finite element method and coupled-mode theory.更多还原