Nonlinear Physics in Soliton Microcombs

Like rulers of light, optical frequency combs consist of hundreds to millions of coherent laser lines, which are capable of measuring time and frequency with the highest degree of accuracy. Used to rely on table-top mode-locked lasers, optical frequency combs have been recently realized in a miniaturized form, namely the microcomb, using monolithic microresonators. Besides a reduction of footprint, microcombs could also achieve parity with traditional frequency combs in performance by mode-locking through the formation of "light bullets" called dissipative Kerr solitons. These soliton microcombs not only serve as a unique platform to study nonlinear physics, but also offer scalable and cost-effective solutions to many groundbreaking applications, spanning spectroscopy to time standards. In this thesis I will trace the physical origin of soliton microcombs, followed by their experimental realization in high-Q silica microresonators. The impact of several nonlinear process on solitons will be discussed, which leads to novel soliton systems, e.g., Stokes solitons and counter-propagating solitons. Utilizing these nonlinear properties, we show that soliton microcombs can be adapted for high-precision spectroscopic applications. In the end, a real-time method for monitoring transient behavior of solitons will be presented