Spontaneous soliton mode-locking of a microcomb assisted by Raman scattering

We successfully control the interaction dynamics between optical parametric oscillation (OPO) and stimulated Raman scattering, leading to the generation of distinct frequency comb states in a microresonator. Through Raman-scattered photons, a Raman comb with a sech2 envelope is demonstrated having a broad RF beat note linewidth of several hundred kHz. Moreover, under a specific coupling regime, we successfully generate self-locked Raman single-solitons which is confirmed by a narrow RF beat note of 25 Hz. Remarkably, this spontaneous Raman soliton is deterministically generated through adiabatic pump frequency detuning without the requirement of external locking mechanisms. Additionally, we identify a frequency comb with an unconventional envelope that can be fitted with a Lorentzian x sech2 function, generated via an anti-Stokes process with respect to the Raman comb.

Automated summary

The interaction dynamics between optical parametric oscillation (OPO) and stimulated Raman scattering are successfully controlled, resulting in distinct frequency comb states in a microresonator. A Raman comb with a sech2 envelope is demonstrated through Raman-scattered photons, with a broad RF beat note linewidth. Furthermore, self-locked Raman single-solitons are generated under a specific coupling regime, confirmed by a narrow RF beat note. This study has significant implications for the generation and control of frequency combs.