【作者】 李俊；

【导师】 宋跃江；

【作者基本信息】 南京大学 ， 光学工程（专业学位）， 2020， 硕士

【摘要】 回音壁模式微腔通常是尺寸在几十到数百微米的介电微腔,例如微球、微盘和微环,它们可以通过连续的全内反射将光限制在微腔内部。由于回音壁模式微腔具有高品质因子和小模式体积的独特物理特性,因此被广泛应用在传感、低阈值激光、光学滤波和非线性光学等领域。近些年来,由于光子学中的法诺共振具有独特的谱线形状,其光谱线型可以通过调节法诺参数进行改变,所以受到了研究者的重点关注。将法诺共振与回音壁模式微腔相结合,以研究其产生的现象和相关应用,是目前比较热门的研究方向。本论文研究了基于回音壁模式微腔的法诺共振应用以及毫米级微腔中的法诺共振,本论文叙述的具体研究工作如下:（1）探究了高阶法诺共振在薄壁液芯环形微腔中的应用。首先理论上用数值仿真方法分析了不同高阶模式在环形微腔中的渗透深度,以及灵敏度与品质因子之间的关系。其次实验上用氢氟酸溶液减小毛细管壁厚,在其中通入乙醇溶液,通过用光纤锥耦合毛细管微腔激发法诺模式,控制液芯温度,实现了法诺共振波长的可调谐。将这种波长可调谐性应用在环形光纤激光器中,实现了连续线性可调谐的激光输出。（2）研究了锥形微腔中震荡法诺模式的应用。文中首先建立了光纤锥耦合锥形微腔的理论模型,通过公式推导引入共振场与背景场的复数比,该复数比以法诺参数命名。理论分析可知,通过改变光纤锥的耦合尺寸可以改变法诺参数,进而改变法诺共振谱。接着通过在实验中用光纤锥耦合锥形微腔,得到不同光纤锥耦合直径下的透射谱。通过仿真比较,该实验结果与理论曲线非常吻合。进一步,通过调节锥形微腔的耦合直径,实现了共振波长的可调谐。将其应用在光纤激光器中,同样实现了线性可调谐的激光输出。（3）实现了一种毫米级高品质因子微腔的制备。通过利用CO₂激光束对熔融石英预制棒进行整形处理,得到了品质因子平均在5?10⁷以上的毫米级微腔。使用光纤锥耦合这种微腔,能产生品质因子在十的六次方的法诺共振。更多还原

【Abstract】 Whispering gallery mode microresonators are usually dielectric microresonators with sizes ranging from tens to hundreds of microns,such as microspheres,microdisks,and microrings.They can confine light inside the microresonators through continuous total internal reflection.Because of the unique physical characteristics of high quality factor and small mode volume,whispering gallery mode microresonators are widely used in the fields of sensing,low-threshold laser,optical filtering and nonlinear optics.In recent years,due to the unique shape of the Fano resonance in photonics,the spectral line shape can be changed by adjusting the Fano parameter,so it has attracted the attention of researchers.Combining Fano resonance with whispering gallery mode microresonators to study the phenomena and related applications is currently popular research direction.This paper studies the application of Fano resonance based on the whispering gallery mode microresonators and the Fano resonance in millimeter-scale microresonators.The specific research work described in this paper is as follows:(1)The application of high order Fano resonance in a thin-walled liquid core microring is explored.First,the penetration depth of different high order modes in the microring and the relationship between sensitivity and quality factor are analyzed theoretically by numerical simulation.Secondly,the wall thickness of capillary is reduced with hydrofluoric acid solution,and ethanol solution is injected into core.The fiber taper is used to couple the capillary microresonator to excite the Fano mode,and the temperature of the liquid core is controlled,we achieve tunability of Fano resonance wavelength.This wavelength tunability is applied to a ring fiber laser to achieve a continuously linear tunable laser output.(2)The application of the oscillating Fano mode in a conical microresonator is studied.A theoretical model of fiber taper coupling conical microresonator is first established in this paper.The complex ratio of the resonance field to the background field is introduced through the formula.The complex ratio is named after the Fano parameter.Theoretical analysis shows that by changing the coupling size of the fiber ctaper,the Fano parameter can be changed,and then the Fano resonance spectrum can be changed.Then,in the experiment,fiber taper is used to couple the conical microresonator to obtain transmission spectra at different fiber taper coupling diameters.The simulation results show that the experimental results are in good agreement with the theoretical curves.Further,by adjusting the coupling diameter of the conical microresonator,the resonance wavelength can be tuned.Applying it to a fiber laser also achieves a linearly tunable laser output.(3)The fabrication of high quality factor microresonators with millimeter-scale is realized.By using a 2CO laser beam to shape the fused silica preform,millimeter-scale microresonators with quality factor of average above 75?10 are obtained.Using the fiber taper to couple such microresonators can produce Fano resonance with quality factor in the sixth power.更多还原