Date of Award
Doctor of Philosophy (PhD)
In a nonlinear optical system, the output optical fields are not linearly related to the power of input optical fields. On the contrary, the input fields could modify the optical properties of the system comprehensively, inducing a change in the transmission/reflection spectrum or the generation of light at different wavelengths. However, such nonlinear phenomena often require enormous optical pump power to be observed. In Whispering Gallery Mode (WGM) microresonators with high quality (Q) factors and small mode volumes (V), an intense intra-cavity optical intensity could be achieved by the spatial confinement and the temporal accumulation of the input light. Thus, enhanced nonlinear effects could be realized with moderate input power in a small-footprint device, which has shown promise in areas including communication, all-optical controlling, sensing, measuring and light generation with wavelength conversion.In the dissertation, I introduce several designs and demonstrations of WGM-based systems for enhanced nonlinear effects. We study the opto-thermal dynamics and stability in polymetric WGM resonator systems and propose a new type of WGM microdroplets of hydrogel containing aqueous solution of sensing targets. Such design allows us to directly fabricate the target of interest into a high-Q optical microresonators, where greatly enhanced optical field could be applied to interrogate the Raman signal of the targets. We further study the WGM enhancement of Raman spectroscopy by combining it with nanoplasmonic hotspots. The coupling between the WGMs and plasmonic modes provides a two-fold enhancement of the pump field and we demonstrated the enhancement of the Raman signal pumped with the coupling mode.
Lan L. Yang
Matthew M. Lew, Chuan C. Wang, Li L. Yang, Xuan X. Zhang,
Available for download on Thursday, May 21, 2026