Research On Optical Properties Of Whispering-gallery-Mode Microresonator

Whispering-gallery-mode (WGM) microresonator has high quality factor and small mode volume, and it has been widely used in fundamental physics and some real applications such as sensing. So far, WGM microresonators with various shapes including microcylinders, microspheres, microbottles, microtoroids, and microdisks have been realized. This thesis takes several WGM microresonators with different shapes as the research object, and studies their optical properties by using the fiber taper as a coupler. Firstly, the fiber microcylinder is studied and it is shown that the position of the fiber taper placed and the polarization of the input light have great influence on the transmission spectrum. Further, a sausage-like microresonator (SLM) is proposed by-making two microtapers on a fiber microcylinder. The transmission spectra of several SLMs with different lengths as well as the tunability of the resonance wavelength of the SLM are studied. Then, the microbottle is fabricated using a new method where the gravity is used to pull the fiber that is heated by a CO2 laser. In the microbottle, the ringing phenomenon is observed and it is found that a decaying function can be used to describe the light field in the cavity to explain the ringing phenomenon. Finally, based on the ringing phenomenon observed in the WGM microresonators, a new sensing method is proposed and experimentally demonstrated in the microsphere.