Broadband Continuous Kerr–Raman Comb Generation via Transverse Mode Interaction in Microcavities

Broadband optical frequency combs (OFCs) based on whispering gallery mode (WGM) microcavities have wide-ranging applications in coherent communication, optical clocks, and precision measurement. This paper investigates the generation of stimulated Raman combs (SRC) under transverse mode interactions. By adjusting the pump detuning, SRC can switch between multi-mode and single-mode states. Further, the Kerr-Raman dynamics in the microcavity are explored, and an SRS-LLE model is constructed. By increasing the intracavity power, the spectral bandwidth of the single-mode SRC is gradually expanded, leading to the perfect integration of SRC and Kerr OFC. Experimentally, the Raman and Kerr OFCs are successfully integrated at a pump power of ∼200 mW, generating an OFC with a wavelength range from 1515 nm to 1700 nm. This achievement enhances the understanding of Raman comb dynamics and offers new approach for the generation and switching of broadband Raman sources in microcavities.