Physics and Applications of Optical Nonlinearity in High-Q Microresonators

Author: Yuan, Zhiquan

Year: 2024

Degree: Dissertation (Ph.D.)

Advisor: Vahala, Kerry J.

Committee Members: Faraon, Andrei; Atwater, Harry Albert; Painter, Oskar J.; Vahala, Kerry J.

Option: Applied Physics

DOI: 10.7907/vj6e-wr82

Abstract

Optical microresonators trap light in compact volumes at discrete resonant frequencies. Benefiting from the ultra-low propagation loss, the electromagnetic wave intensity is greatly enhanced. Due to the pronounced light confinement, nonlinear optical effects are significantly magnified in the microresonators. In this thesis, I investigate various nonlinear optical phenomena using high quality factor silica wedge and fully-integrated thin film silicon nitride microresonators. The exploration begins with Kerr nonlinearity-induced soliton microcombs followed by their application in mid-IR band gas spectroscopy. The generation of solitons under normal dispersion conditions, which frustrate soliton formation, is then considered. Subsequently, attention is directed towards stimulated Brillouin lasers and their frequency noise performance, including long-term frequency stabilization based on the built-in temperature reference and validation of two modification factors affecting short-term fundamental linewidth. Along this journey, a novel method for calibrating ultra-narrow laser linewidths is introduced. Lastly, this method is employed to measure the narrow linewidth of a visible laser generated through second harmonic generation in silicon nitride resonators.

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