Date of Award
Doctor of Philosophy (PhD)
Optical whispering-gallery-mode (WGM) microresonators with high quality factor and small mode volume are able to significantly enhance light-matter interaction, which is promising for the studies of nonlinear optics as well as for the sensing applications. Due to the enhanced intracavity optical intensity, the radiation pressure of the optical field can be strong enough to be coupled to the mechanical modes of the microresonator. This coupling between the optical mode and mechanical mode is referred to as the cavity optomechanical coupling, which has enabled many interesting effects including optomechanical heating and cooling, optomechanically induced transparency, phonon lasers and chaos.In this dissertation, we study the physical phenomena and the sensing applications based on the WGM microtoroid resonators as a cavity optomechanical system. We first investigate the interaction between the optomechanical effect and thermo-optic nonlinearity, which is usually inevitable in WGM microresonators. We found that the optomechanical effect can induce a new type of thermal bistability, and the experimental approach we use is helpful in evaluating the detuning in the presence of optomechanical oscillations. Second, we propose and demonstrate an enhanced dissipative sensing of acoustic waves with the optomechanical solitons. Optomechanical solitons belong to a novel kind of nonlinear mechanical state found in the microtoroid. In the experiment, we confirm that the broad frequency spectrum of the solitons can assist the detection of low-frequency signals by a resonance-like effect. In the third part, we will discuss the development and characterization of the packaged polymer-enhanced microtoroid sensors. Due to the large mechanical susceptibility of polymers, the introduction of polymer materials can improve the sensitivity to mechanical perturbations such as dynamical magnetic force, static force, and photoacoustic ultrasonic waves.
Song Hu, Matthew Lew, Chuan Wang, Li Yang,
Available for download on Saturday, April 26, 2025