| The whispering-gallery mode microdisk or microsphere resonators have supercompact size, high energy storage, very narrow resonance bandwidth, and high sensitivity. These appealing properties have attracted much attention in the realization of microlasers, narrow filters, optical switching, biosensing, high resolution spectroscopy, and so on. In this dissertation, the optical and energy transport phenomena of whispering-gallery mode resonance and its potentials in some optical sensing applications will be characterized. A 2D theoretical analysis is first presented based on the method of separation of variables and by deriving several appropriate and reasonable boundary conditions to describe the electrical field distribution at resonance modes. This analytical model can precisely predict the intrinsic resonance frequencies of isolated whispering-gallery mode resonators. To consider the coupling of light-delivery waveguides with resonators and investigate the resonance phenomena of the resonator-waveguide system and/or device, simulations using a Finite Element Method solver of Maxwell's equations are conducted. The results indicate the influences of the geometric dimensions, refractive indices, gap distances, and excitation wavelengths on the main characteristics of the resonance modes such as the quality factor Q, the finesse, the mode intensity, and so on. Furthermore, the gap effects are detailedly studied by both theoretical analysis and simulation modeling. The optimal gap for the maximum coupling efficiency and the optimum gap for the best sensing application of the whispering gallery mode resonators are introduced and discussed based on simulation data and theoretical estimations. Three prospective applications of the whispering gallery mode-based sensors are introduced and proof-of-concept studies are demonstrated. The design schemes and fabrication process of the on-chip resonance device made of the Si3N4/SiO2 material system using nanofabrication technology are presented and discussed. Finally, the experimental setup is introduced and some test results are shown in the last part of this dissertation. |
