光纤耦合回音壁模微球腔特性及其选模技术研究

发布时间：2018-03-26 18:45

本文选题：回音壁模式　切入点：微球腔　出处：《南京邮电大学》2017年硕士论文

【摘要】：回音壁模式(Whispering Gallery Mode,WGM)微腔因具有品质因子高、腔内能量密度大、透射谱线窄等特点而在光纤通信及传感领域具有重要的应用价值。窄带选模器作为光通信网中必不可少的关键器件,对提高光信息发送速率、提高信号信噪比等方面起着重要作用,WGM微腔上述特点,使其成为一类理想的窄带选模器。此外,WGM微腔对外界环境变化极为敏感的特性同样使其在传感领域有着广泛应用。本文主要围绕WGM微球腔窄带选模器和传感器,研究WGM微球腔选模器的全光调谐特性以及混合介质WGM微腔与表面等离子体共振(Surface Plasmon Resonance,SPR)效应相结合的传感增强效应。本论文首先介绍了WGM微腔的研究进展、微腔的类别及应用领域,简要论述了WGM微球腔的电磁场理论及特性参数,对比了几种常见的微腔耦合方案,综合考量选定锥形光纤与微球腔进行耦合,并简述其耦合理论。在此基础上建立了微球-锥形光纤耦合的有限元模型,研究纯介质微球的参数以及耦合条件对WGM共振特性的影响;采用多层介质材料构造Q值更高、谱线更窄的混合介质微球腔,并对混合介质WGM微球腔参数进行优化。提出一种表面等离子体(Surface Plasmons,SP)增强型混合介质WGM微腔传感器,通过混合介质微腔与SPR效应相结合提高了现有微腔传感器的灵敏度。论文实验研究了两种微球腔制备方法:包括电弧放电和CO2激光器熔融法,测试了微球表面粗糙度,确定后者形成的微球腔Q值更高,达到107量级。利用精密位移平台搭建了微球腔-锥形光纤耦合系统,在1550 nm波段实验获得了耦合效率达90%以上、Q值约为2.1×107、透射峰谱线3dB带宽1.2 nm的WGM透射谱。在此基础上搭建了基于WGM微球腔窄带选模的光纤激光器实验系统,获得了1550 nm波段功率为200 mW,3dB带宽0.01 nm,边模抑制比38 dB,全光波长调谐范围达60 pm的全光纤激光输出。
[Abstract]:Because of the high quality factor and the high energy density in the cavity, the microcavity of whispering Gallery modem (WGM) is a kind of echo-wall mode. The narrow transmission line has important application value in the field of optical fiber communication and sensing. As an essential key device in optical communication network, narrowband mode selector can improve the transmission rate of optical information. Improving signal-to-noise ratio (SNR) plays an important role in WGM microcavity. It is a kind of ideal narrow-band mode selector. In addition, it is also widely used in the sensing field because of its sensitivity to environmental changes. This paper focuses on the narrow-band mode selector and sensor of WGM microsphere cavity. The all-optical tuning characteristics of the WGM microsphere cavity selector and the sensing enhancement effect of the mixing medium WGM microcavity combined with the surface plasmon resonance surface Plasmon resonance (SPR) effect are studied. Firstly, the research progress of the WGM microcavity is introduced. This paper briefly discusses the electromagnetic field theory and characteristic parameters of WGM microsphere cavity, compares several common coupling schemes of microcavity, and synthetically considers the coupling between tapered fiber and microsphere cavity. On the basis of this, the finite element model of the coupling of microspheres and conical fibers is established to study the influence of the parameters and coupling conditions of pure dielectric microspheres on the resonance characteristics of WGM. The parameters of WGM microsphere cavity with narrower spectral lines are optimized. A surface plasmon surface enhanced WGM microcavity sensor is proposed. The sensitivity of the existing microcavity sensor is improved by the combination of the mixed dielectric microcavity and the SPR effect. Two fabrication methods of the microsphere cavity, including arc discharge and CO2 laser melting, are experimentally studied in this paper, and the surface roughness of the microsphere is measured. It is determined that the Q value of the microsphere cavity formed by the latter is higher, reaching the order of 107. The coupling system between the microsphere cavity and the tapered fiber is built by using the precision displacement platform. The WGM transmission spectra with coupling efficiency of more than 90% and transmission peak line 3dB bandwidth of 1.2nm have been obtained by experiments at 1550 nm. An experimental system of optical fiber laser based on WGM microsphere cavity narrowband mode selection has been built. An all-fiber laser with 1550 nm power of 200mW ~ (3) dB bandwidth of 0.01 nm, an edge-mode rejection ratio of 38 dB and a wavelength tuning range of 60 pm has been obtained.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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