回音壁模式球微腔的制备及其应用研究

发布时间：2018-05-18 14:32

本文选题：回音壁模式 + 球微腔　；参考：《浙江师范大学》2015年硕士论文

【摘要】：近年来,具有高品质因子(Q)和低模式体积(V)的回音壁模式微腔吸引了众多学者的研究兴趣。光学回音壁模式(Whispering Gallery Mode, WGM)是指在微腔内部,光以全反射的形式传播,使得光被约束在腔内并沿着赤道面绕行,当光程等于波长整数倍,即满足相位匹配条件时,会产生等间隔分立的共振模,这种电磁场模式被称作回音壁模式。回音壁模式微腔尺寸极小,腔体内部能量密度极高,并且制作过程简单方便,成本低廉,易于集成。基于以上这些特性,回音壁模式微腔作为重要的光学器件被应用于众多领域,例如非线性光学、腔量子电动力学、光学滤波器、高灵敏度传感器和低阈值激光器等。本文从理论和实验两个方面出发对基于回音壁模式的光学微腔进行了研究探索。具体的研究内容包括以下几个方面：首先,回顾了近些年来回音壁模式光学微腔的研究背景和研究进展,并结合具体实例简单介绍了回音壁模式光学微腔的应用情况。其次,介绍回音壁模式光学微腔和锥形光纤的模式理论基础。通过结合Maxwell方程和球微腔的边界条件,对球微腔中的模式分布进行分析,并对球微腔的基本特性进行了简要介绍；采用商业软件COMSOL Multiphysics提供的有限元数值分析方法对球微腔中的模式进行数值模拟,得到了球微腔内赤道面上回音壁模式的分布情况。利用光射线法对锥形光纤的模式特性进行了简单探讨,并使用COMSOL Multiphysics软件对不同纤芯直径的光纤横截面上的光场分布进行仿真模拟,得到其光场分布。将锥形光纤与球微腔耦合系统作为整体,对其耦合理论基础进行了分析。然后,搭建了使用氢气火焰加热法制备锥形光纤的实验系统,制备出实验需要的、直径在微米量级的锥形光纤。设计了高温熔融冷却法制备球微腔的实验系统,使用二氧化碳激光器加热熔融单锥光纤,制备出不同直径(约60 μm-125μm)的球微腔。使用宽带光源,光谱分析仪和CCD监控装置搭建了锥形光纤与光学微腔耦合系统,测量球微腔的品质因子。利用球微腔与锥形光纤耦合系统实现了基于球微腔与锥形光纤耦合系统的掺铒光纤激光器,实验中使用掺铒光纤作为增益介质,球微腔作为滤波器和反射镜使用,与锥形光纤进行耦合,使用980nmm激光二极管作为泵浦源,实现波长为1563.95 nm的激光输出,该激光器的阈值为42.86mW,最大输出功率为0.1 mW。最后,使用氢气火焰加热法制备锥形光纤的实验系统制备出直径渐变的圆柱形微腔。对锥形光纤与圆柱形微腔耦合系统进行测试,得到圆柱形微腔的品质因子。使用直径渐变圆柱形微腔(直径约为21μm-38.7μm),实现了基于直径渐变圆柱形微腔的可调谐滤波器。实验中圆柱形微腔的位移为60,um,得到共振波长移动量为178.8nm,共振波长对位移量的变化关系为2.98nm/μm。
[Abstract]:In recent years, echo-wall microcavities with high quality factor (Q) and low mode volume (V) have attracted much research interest. Optical echoing Gallery Mode, WGM) means that light propagates in the form of total reflection inside the microcavity, so that the light is confined in the cavity and travels around the equatorial plane. When the optical path is equal to an integer multiple of the wavelength, that is, the phase matching condition is satisfied. An equally spaced discrete resonant mode is produced, which is called the echo wall mode. The size of microcavity in echo mode is very small, the energy density inside cavity is very high, the fabrication process is simple and convenient, the cost is low, and the integration is easy. Based on these characteristics, echo wall mode microcavity is used as an important optical device in many fields, such as nonlinear optics, cavity quantum electrodynamics, optical filter, high sensitivity sensor and low threshold laser. In this paper, the optical microcavity based on echo wall mode is studied theoretically and experimentally. The specific research contents include the following aspects: firstly, the research background and research progress of echo wall mode optical microcavity in recent years are reviewed, and the application of echo wall mode optical microcavity is briefly introduced with concrete examples. Secondly, the mode theory of echo-mode optical microcavity and tapered fiber is introduced. Based on the Maxwell equation and boundary conditions of the spherical microcavity, the mode distribution in the spherical microcavity is analyzed, and the basic characteristics of the spherical microcavity are briefly introduced. The finite element numerical analysis method provided by commercial software COMSOL Multiphysics is used to simulate the mode in the spherical microcavity, and the distribution of the echo wall mode on the equatorial surface of the spherical microcavity is obtained. The mode characteristics of tapered fiber are discussed by means of light ray method, and the optical field distribution on the cross section of fiber with different core diameters is simulated by COMSOL Multiphysics software, and the light field distribution is obtained. The coupling theory of tapered fiber and spherical microcavity is analyzed. Then, an experimental system for fabricating tapered fiber by hydrogen flame heating method was built, and the tapered fiber with the diameter of micron was prepared. An experimental system for the fabrication of spherical microcavities by high temperature melt cooling was designed. The spherical microcavity with different diameters (about 60 渭 m ~ 125 渭 m) was fabricated by heating the fused single-cone fiber with carbon dioxide laser. The coupling system of tapered optical fiber and optical microcavity was constructed by using broadband light source, spectrum analyzer and CCD monitoring device, and the quality factors of spherical microcavity were measured. The erbium-doped fiber laser based on the coupling system of spherical microcavity and tapered fiber is realized by using the coupling system of spherical microcavity and tapered fiber. In the experiment, erbium-doped fiber is used as gain medium and spherical microcavity as filter and reflector. The 980nmm laser diode is used as the pump source to realize the laser output at 1563.95 nm. The threshold of the laser is 42.86 MW and the maximum output power is 0.1 MW. Finally, the tapered fiber was fabricated by hydrogen flame heating method. The coupling system of tapered fiber and cylindrical microcavity is tested and the quality factor of cylindrical microcavity is obtained. The tunable filter based on the diameter gradient cylindrical microcavity (about 21 渭 m ~ 38.7 渭 m) is realized. In the experiment, the displacement of the cylindrical microcavity is 60 渭 m, and the shift of the resonant wavelength is 178.8 nm, and the relation between the resonant wavelength and the displacement is 2.98nm/ 渭 m.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN25

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