长周期光纤光栅的特性及应用研究
文献类型：学位论文
| 作者 | 高侃 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 方祖捷 |
| 关键词 | 光纤通信 光纤传感 长周期光纤光栅 EDFA增益平坦滤波器 |
| 其他题名 | Studies on Characteristics and Applications of Long-period Fiber Gratings |
| 中文摘要 | 随着信息技术的不断发展，光纤技术在通信领域和传感领域中应用的范围正越来越广泛，并起到越来越重要的作用。光纤光栅的出现，被誉为是继掺饵光纤放大器后光通信发展史上的又一次重大技术突破。而长周期光纤光栅作为一种新型的光纤光栅，由于其带宽宽、后向反射低、插入损耗小、对外界环境变化的反应灵敏度高、制作简单、成本低廉等优点，受到国内外广大学者的关注。发展短短数年，已经显示出了极为广阔的应用前景。本论文针对长周期光纤光栅的特性和应用，进行了比较全面的理论及实验研究，所做的工作主要包括以下几个方面：从分析单模光纤中纤芯基模和包层模的色散方程和场分布出发，结合祸合模理论，对长周期光纤光栅的光谱特性进行了详细的分析和模拟仿真，为开展对长周期光纤光栅的研究工作打下良好的理论基础。从理论上研究了莫尔技术在长周期光纤光栅制作中的应用，研究表明利用莫尔效应可以制作出高性能的兀相移长周期光纤光栅和纯变迹长周期光纤光栅。对长周期光纤光栅包层模倏逝波，包括两个长周期光纤光栅之间的祸合，以及长周期光纤光栅与拉锥光纤之间的藕合，进行了理论和实验研究，为开发长周期光纤光栅组合器件，以及长周期光纤光栅同其他光纤元器件的组合器件，提供了可能的方案。对用紫外曝光方法在载氢光纤上制作长周期光纤光栅的三个阶段的工艺，包括载氢、光栅刻制、退火，进行了比较全面的探讨和研究，提出了利用适当降低光纤载氢量，增加曝光时间来提高长周期光纤光栅热稳定性的方法，提高了光栅制作的成品率：同时提出了在光栅的制作过程中应用均匀曝光技术来改变光栅祸合特性的方法，提高了光栅制作的灵活性。利用上述的光栅制作工艺，结合一定的优化算法，利用三根长周期光纤光栅的串联制作了用于EDEA增益平坦的滤波器，取得了良好的应用效果。全面地研究了长周期光纤光栅的敏感特性，包括温度响应、应变响应、折射率响应、弯曲响应、扭转响应等，分析了波导色散因子的重要作用。根据长周期光纤光栅的弯曲特性，结合应变膜片的原理，设计了用于气体、液体压力传感的光纤传感器，可以获得0.1KPa的压强测量分辨率。通过在长周期光栅表面镀金属膜并通以电流的方法对长周期光纤光栅进行了温度调谐的研究；并对金属化长周期光纤光栅前后谐振波长的漂移进行了理论的研究。对串联长周期光纤光栅的透射光谱特性及其温度特性进行了详细的理论和实验研究，提出了利用测量谐振小峰间距来估算长周期光纤光栅波导色散因子的方法。研究了在保偏光纤上制作出来的长周期光纤光栅的光谱特性，发现了保偏长周期光纤光栅特殊的温度和应变响应特性，即同一阶快、慢轴谐振峰的温度及应变响应系数具有相反的符号，并且对应与快轴或慢轴的不同阶谐振峰的温度及应变响应系数的符号也相反。根据保偏长周期光纤光栅的特性提出了可调谐光纤型起偏器和偏振分束器的设计方案。 |
| 英文摘要 | With developments of information technology, the optical fiber has been widely used in the field of communication and sensing, and plays more and more important roles. The invention of optical fiber gratings was considered as the second revolution of optical fiber technology. The long-period fiber grating (LPFG) as a new kind of fiber gratings has been studied by many researchers all around the world recently, and has got great progresses in a few years. It is used in many fields for its advantages such as low insert-loss, broad-band, low back-reflection, sensitive to the changes of environments, low-cost and easy to be fabricated. In this paper, the characteristics and applications of LPFGs were studied theoretically and experimentally. The main research contents include: The spectral characteristics of LPFGs were investigated in detail and simulated numerically to lay a theoretical platform for the researches of LPFGs, based on the dispersion relation and mode fields of the core mode and cladding modes in a single mode fiber, by using the coupled mode theory. The transmission spectra of long-period moire gratings were simulated by the method of transfer matrix. The results of analysis indicate that the moire" technology can be well applied in fabricating the high-performance phase-shifted and apodised long-period fiber gratings. Evanescent-field coupling of cladding modes, including the coupling between two LPFGs and the coupling between a LPFG and a tapered fiber, was investigated both theoretically and experimentally, which provided some possible schemes for LPFG devices combined with other fiber components. Three main technical steps in fabricating LPFG by UV exposure, hydrogen-loading, grating-inscribing and annealing, were described and discussed in detail. It was found in the experiments that if the solubility of H2 in the hydrogen-loaded fiber was lowered and the time of UV exposure was extended, the thermal stability of LPFG could be improved greatly, resulting in higher reproducibility. It was also found that by using uniform UV exposure in different steps of grating-fabricating, the spectral characteristics of LPFG could be changed. By using all these techniques and the genetic algorithm, a gain-flattening filter for EDFA consisting of three LPFGs was designed and fabricated, which achieved a good effect for real applications. The sensitivity of LPFGs to temperature, stress, bending, refractive index and torsion were investigated theoretically and experimentally. The role of waveguide dispersion factor y was analyzed emphatically. Based on the bending sensitivity of LPFG, a novel pressure sensor incorporated with a strain diaphragm structure was proposed and demonstrated. By the method of detecting the change of the transmission output power at a fixed wavelength within the rejection band, the pressure inside the diaphragm could be measured. The resolution of this device could reach to lO-4MPa, which is suitable to real applications. The characteristics of a tunable filter based on metal-coated LPFG were investigated. By applying different current to the metal coating, the resonant wavelengths of LPFGs could be tuned, with the spectrum shape changed little. The mechanism of the wavelength-shift of LPFG before and after metal-coating was also discussed theoretically. Based on the Mach-Zehnder effect between the core mode and the cladding modes, the interference fringes are formed by a pair of cascaded LPFGs. Theoretical analyses show that the wavelengths of these fringes and their spacing are functions of the waveguide dispersion factor γ. By measuring the characteristics of the transmission spectra of cascaded LPFGs, the absolute value of γ can be obtained, which provided a method for its direct measurement. The characteristics of LPFGs written in Panda fiber are presented. Both the strain and temperature responses show good linear characteristics. It was observed that the temperature and strain responses for fast and slow axes of different cladding modes have opposite behaviors. A qualitative explanation is presented to the phenomena. The design schemes of tunable fiber polarizer and polarization-splitter based on LPFGs were also proposed. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15331]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 高侃. 长周期光纤光栅的特性及应用研究[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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