回音壁光学微腔是基于全反射原理束缚光的介质微腔，它的品质因子能达到10^8以上，在传感技术中有重要的应用。传统的回音壁微腔传感原理依赖于测量光传输谱线的移动量、劈裂量或者展宽量，但激光波长的漂移、光纤锥的振动等会影响这些传统方法的传感精度，尤其是小尺寸纳米颗粒的传感面临严峻的挑战。振铃现象是一种光学干涉现象，本项目将研究基于振铃现象的回音壁微腔传感。这是一种新型的传感原理，与传统方法相比其抗干扰能力强，对激光波长的漂移、光纤锥的振动等噪声因素不敏感，具有更高灵敏度的检测能力，并且能用于快速变化过程的传感。本项目将分别实验研究掺铒和不掺铒的回音壁微腔振铃现象，并实现小尺寸纳米颗粒的传感；同时，为进一步降低系统复杂度和减少光纤锥的振动噪声，我们还将烧制带耦合光纤锥的新型回音壁光学微腔，并利用它研究振铃现象及其在纳米颗粒传感中的应用。所获研究成果将促进高灵敏检测技术的发展。

Whispering-gallery-mode optical microcavity is a kind of dielectric microcavity that confines light based on the principle of total reflection. Its quality factor can be larger than 10^8 and has an important application in sensing. The traditional sensing mechanisms of whispering-gallery-mode optical microcavity depend on measuring the shift, splitting or broadening of the optical transmission dips, but the noise like the drift of the laser wavelength and the vibration of the optical fiber taper can affect the accuracy of these sensing mechanisms, which especially leads to a severe challenge in sensing small nanoparticles. Ringing phenomenon is a kind of interference phenomenon, and the project will investigate ringing phenomenon based whispering-gallery-mode optical microcavity sensing. It is a new kind of sensing mechanism, and compared to the traditional mechanisms it has a strong anti-interference ability and is insensitive to the noise like the drift of the laser wavelength and the vibration of the optical fiber taper. The ringing phenomenon based whispering-gallery-mode optical microcavity sensing has higher sensibility and can sense fast process. We will experimentally investigate the ringing phenomenon in erbium-doped and non-erbium-doped whispering-gallery-mode optical microcavity and use it to sense small nanoparticles. In order to further reduce the system complexity and reduce the vibration of the optical fiber taper, we will also investigate the fabrication of a new kind of whispering-gallery-mode optical microcavity with coupled optical fiber taper, the ringing phenomenon in this microcavity and its application in sensing nanoparticles. The results of the project will promote the development of highly sensitive detection technology.