High-efficiency dissipative Kerr solitons in microresonators

Doktorsavhandling, 2022

The microresonator comb (microcomb) is a laser source that generates equally spaced coherent lines in the spectral domain. Having a chip-scale size and the potential of being low cost, it has attracted attention in multiple applications. Demonstrations have included high-speed optical communications, light detection and ranging, calibrating spectrographs for exoplanet detection and, optical clocks. These experiments typically rely on the generation of a dissipative Kerr soliton (DKS) --- a temporal waveform that circulates the microresonator without changing shape. However, these DKS states have thus far been limited in certain technical aspects, such as energy efficiency, which are essential for realizing commercial microcomb solutions.

This thesis studies the dynamics of DKSs in microresonators aiming at developing a reliable and high-performing microcomb source. The investigation will cover DKSs found both in the normal and anomalous dispersion regime of silicon nitride microresonators. The performance of microcombs in terms of line power is numerically explored in single-cavity arrangements for telecommunication purposes. DKSs generated in linearly coupled microcavities are investigated, revealing exotic dynamics and improved performance in terms of power efficiency and DKS initiation. These studies facilitate reliable energy-efficient microcombs, bringing the technology a step closer to commercial use.