Thermally stable initiation of dissipative Kerr solitons in photonic molecules

Paper in proceeding, 2023

Dissipative Kerr solitons (DKSs) have been heavily researched in the last decade. These are robust waveforms that are generated in a single anomalous-dispersion microresonator. Microcombs corresponding to a single DKS circulating in a microcavity have been demonstrated to be robust, enabling multiple different applications, such as spectroscopy and telecommunications [1]. However, the fact that the continuous-wave (CW) laser has to be operated far red-detuned from resonance leads to practical limitations. One such limitation is low conversion efficiency, due to much of the pump bypassing the cavity. A second limitation is a challenging DKS initiation, which is a consequence of the red side of resonance being thermally unstable in the majority of integration materials, often requiring time-sensitive control schemes [2], or auxiliary cooling lasers [3], to enable the initiation. In a recent work, we addressed the limited conversion efficiency by shifting the pumped resonance via an avoided mode-crossing enabled by linear coupling to an auxiliary cavity [4]. Here, we show that this coupled-cavity arrangement (a photonic molecule) allows the initiation process, including the final DKS state, to be operated with the CW laser consistently located on the blue side of the pumped resonance. This thermal stabilization leads to a robust initiation scheme, which is not readily available for DKSs in single anomalous-dispersion cavities.