【作者】 李宏亮；

【导师】 张某巍；

【作者基本信息】 清华大学 ， 电子科学与技术， 2011， 硕士

【摘要】 光纤中的双峰布里渊增益机制是近年来光纤非线性光学的研究热点之一。本论文结合国家自然科学基金项目“光子晶体光纤中的异常布里渊散射与消闭锁光纤激光陀螺的论证”，对光纤中双峰和多峰布里渊增益（BGS）的实现及其应用进行了实验和理论研究。实验实现了异质光纤环腔双向双波长多模布里渊光纤激光器（BFL），并论证了其陀螺效应。采用两段具有不同布里渊增益特性的光纤构成异质光纤环，实现光纤中的双峰布里渊增益机制。实验实现了异质光纤环腔BFL的双向双波长多模激射，并实验测试了该结构的陀螺效应。在实验测试范围内，没有观察到该结构陀螺的闭锁现象，同时根据环腔转动时拍频信号频率相对于环腔静止时拍频的频移可以明确判断环腔转动方向，提供了一种实现布里渊光纤陀螺（BFOG）的新思路。实验实现了异质光纤环腔双向双波长单模BFL。理论分析了单耦合器结构异质光纤环腔产生强谐振增强效应的条件和利用腔长反馈控制技术实现环腔单纵模锁定的机制，并利用该技术实现了异质光纤环腔BFL的单向单模稳定激射。通过对异质环腔双向单模稳定激射条件的分析，实现了异质光纤环腔BFL的双向单模激射。对影响双向单模激射稳定性的几个关键问题的解决方法进行了实验探索，分析了实验系统改进方向。理论研究了铝/锗（Al/Ge）共掺w型石英光纤中双峰/多峰布里渊增益特性的实现。受光子晶体光纤中异常布里渊增益谱形成机制的启发，通过在石英光纤中掺入氧化铝（Al₂O₃）和二氧化锗（GeO₂），设计新型光纤结构实现双峰布里渊增益特性。提出该类型光纤中的声波模式耦合机制，理论分析了光纤结构和材料参数对耦合特性的影响，指出可利用声波模式耦合实现光纤中特殊布里渊增益谱的设计。理论分析了温度和应力变化对该结构光纤中布里渊增益特性的影响，通过光纤设计实例，表明其在多物理量分布式传感方面的应用潜力。更多还原

【Abstract】 The dual-peak Brillouin gain mechanism in optical fibers is one of thehot topics in researches of nonlinear fiber optics in recent years. Supported bythe project of Natural Science Foundation of China “Abnormal Brillouinscattering effect in photonic crystal fibers and its application in fiber lasergyroscope without lock-in effect”, this dissertation studies the realization ofdual-peak/multi-peak Brillouin gain spectra (BGS) in fibers and theirapplications experimentally and theoretically.Utilizing the hybrid fiber ring as a dual-peak gain medium, bi-directionaldual-wavelength multi-mode lasing of Brillouin fiber laser (BFL) based on anunbalanced Mach-Zehnder interferometer (UMZI) hybrid fiber ring cavity isexperimentally realized. Its effect as a gyroscope is demonstrated. The scalefactor is measured as1.0305kHz/(deg/s), which agrees well with the result oftheoretical analysis. The rotating direction of the cavity can be clearlydistinguished through the direction of frequency shift. The lock-in effect isnot observed in the experiment.The single-mode lasing of bi-directional dual-wavelength BFL based onthe hybrid fiber ring cavity with one fiber coupler is experimentally realized.The condition of pump oscillation enhancement and bi-directionalsingle-mode lasing of this cavity are analyzed theoretically. Utilizing thefeedback loop technique, a stable uni-directional single-mode lasing of thisBFL is realized under uni-directional pump and a bi-directionaldual-wavelength single-mode lasing is realized under bi-directional pump.The Brillouin frequency shifts of the two lasing modes are10.57GHz and10.51GHz, respectively, with3dB linewidths of lasing modes being~150Hz.The crucial problems influencing the stability of bi-directionaldual-wavelength single-mode lasing are discussed.According to the influence of doping on the acoustical characteristics of silica material, a novel fiber structure is proposed to achievedual-peak/multi-peak Brillouin gain by acoustical mode coupling. Theinfluences of structural and material parameters of fiber on the mode couplingproperties are analyzed theoretically. A specific fiber design with multi-peakBGS is given and its responses on temperature and tensile strain are analyzed.The theoretical analysis shows that the accuracies of discriminativemeasurement of temperature and strain by this fiber are about1.4℃and33με, respectively, which indicates a potential in the application of distributedBrillouin temperature and strain sensing.更多还原