可调谐光学回音壁模式微腔实验研究

发布时间：2018-12-13 13:51

【摘要】：近年来,基于光学微腔的回音壁模式(Whispering Gallery mode,WGM)吸引了众多学者的研究兴趣。可调谐的回音壁模式在滤波、光开关和传感测量中有着极其重要的价值。本文利用硅基材料良好的热光效应、自由载粒子吸收和多光子吸收效应,分别以微管和光子晶体光纤作为光学谐振腔,对回音壁模式的谐振频率和幅度调谐进行了研究。主要的研究内容如下:①采用传输矩阵法分析微管谐振腔振荡频率的传输特性,并利用有限元原理和COMSOL软件理论仿真微光纤近场耦合激发谐振腔的回音壁模式,研究了耦合距离和微管壁厚对谐振模式的影响;实验研究了耦合距离和光波偏振态对回音壁模式的影响。②采用熔融拉锥技术,利用二氧化硅微管和电热丝制作可调谐的回音壁模式电谐振腔,理论推导得知电致热调谐可以实现回音壁模式的大范围调谐;实验测试电谐振腔获得品质因数104数量级,自由光谱范围为0.8nm以及信噪比高达4.3d B的回音壁模式;通过对电热丝通以恒定电流,实现回音壁模式0.57nm的漂移,对应的电流大小为200m A,消耗的电功率约为0.1m W;实验测试可调谐电谐振腔作为光开关时,响应速度在几百ms数量级上,理论分析通过减少微管壁厚和增加微管长度可以提高响应速度。③提出利用光子晶体光纤作为光学微腔获得高Q、少模的回音壁模式。实验通过六个大孔的光子晶体光纤,获得Q值为104数量级的WGM和Fano模式,模式体积较二氧化硅微管少,并利用多光子吸收和自由载粒子吸收效应实现对光学回音壁模式和Fano模式的幅度光调谐;理论仿真光子晶体光纤作为谐振腔的模场分布,初步解释光子晶体光纤产生的Fano模式,孔状结构致使腔体内的高阶模式被损耗,低阶的回音壁模式在腔体外沿发生模式耦合效应,最终形成Fano回音壁模式。综上,热光非线性效应能够实现超大范围的回音壁模式调谐,自由载粒子吸收和多光子吸收致使腔内损耗增加,谐振模式幅度减少;光子晶体光纤的特殊结构致使Fano回音壁模式的形成。本文所设计的两类回音壁模式可调谐器件在可调谐激光器、光滤波以及光开关等领域具有一定的应用价值。
[Abstract]:In recent years, echo wall mode (Whispering Gallery mode,WGM) based on optical microcavity has attracted many scholars' interest. Tunable echo wall mode is of great value in filtering, optical switching and sensing measurement. In this paper, the resonant frequency and amplitude tuning of echo wall mode are studied using microtubules and photonic crystal fibers as optical resonators, respectively, using the good thermo-optical effect, free carrier particle absorption and multi-photon absorption effect of silicon based materials. The main research contents are as follows: 1 Transmission matrix method is used to analyze the transmission characteristics of microtube resonator oscillation frequency, and the echo wall mode of micro-fiber near-field coupling excited resonator is simulated by using finite element theory and COMSOL software theory. The effects of coupling distance and wall thickness of microtubules on the resonant mode are studied. The effects of coupling distance and polarization state of light wave on the mode of echo wall are experimentally studied. 2 the tunable resonator of echo wall mode is fabricated by using silicon dioxide microtubules and electric heating wire. The theoretical derivation shows that electrothermal tuning can realize the large-scale tuning of the echo wall mode. The experimental results show that the quality factor of the resonator is 10 ~ 4 orders of magnitude, the free spectrum range is 0.8nm and the signal-to-noise ratio (SNR) is as high as 4.3 dB. Through the constant current of electric heating wire, the 0.57nm drift of echo wall mode is realized. The corresponding current is 200mA, and the electric power consumed is about 0.1m W; The experimental results show that the response speed of the tunable electric resonator is in the order of several hundred ms when it is used as an optical switch. It is theoretically analyzed that the response speed can be improved by reducing the wall thickness of microtubules and increasing the length of microtubules. 3 it is proposed to use photonic crystal fibers as optical microcavities to obtain high Q and less mode echo wall modes. Six photonic crystal fibers with large holes were used to obtain the WGM and Fano modes with a Q value of 104.The model volume is smaller than that of silica microtubules. The amplitude light tuning of the optical echo wall mode and the Fano mode is realized by using the multiphoton absorption and the free carrier particle absorption effect. The mode field distribution of photonic crystal fiber as resonator is simulated theoretically, and the Fano mode produced by photonic crystal fiber is preliminarily explained. The low order echo wall mode is coupled on the outer edge of the cavity, and the Fano echo wall mode is finally formed. In conclusion, the thermo-optical nonlinear effect can achieve a large range of echo wall mode tuning. The absorption of free-loaded particles and multi-photon absorption results in the increase of loss and the decrease of resonant mode amplitude. The special structure of photonic crystal fiber leads to the formation of Fano echo wall mode. The two kinds of echo-wall tuners designed in this paper have certain application value in tunable lasers, optical filters and optical switches.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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