Broadband Kerr-Raman frequency combs and soliton mode-locking in microrod resonators

We demonstrate the broadband low-noise Kerr-Raman frequency comb source in an ultrahigh Q microrod resonator, and investigate the mechanisms leading to mode-locked frequency combs. By engineering the interaction between modulation instability and Raman gain, we achieve a wideband Kerr-Raman comb ranging from ~1480 nm to 1700 nm via Raman-assisted four-wave mixing (FWM). Moreover, we can attain a low-noise mode-locked state through laser detuning control, which experiences three distinct stages required for stabilized comb generation. This platform provides potential for applications in ultrafast ranging systems, stimulated Raman scattering microscopy, and high-precision spectroscopy based on integrated microcombs.