Modelling of Kerr and Brillouin active micro-resonators in the silicon nitride platform

Kerr and Brillouin active cavities can be used for parametric light sources creating 10-1000 GHz repetition rate optical frequency combs or lasers with sub Hz linewidth in microscale devices, respectively. Such sources are of particular interest for compact solutions in spectroscopy, ranging and microwave photonics. Combining both effects has been demonstrated in whispering gallery mode (WGM) resonators but with isolated steps using intermodal Brillouin lasing into microcomb generation. Such devices have however not been shown in planar technologies, due to smaller mode population and large difference in Kerr and Brillouin strength. However, multi-layer silicon nitride waveguide structures in a standardized platform shows comparable and adjustable Brillouin and Kerr gain [1]. Using a model consisting of two Lugiato-Lefever equations (LLEs) coupled via acoustic modes we show for standard silicon nitride waveguides an adjustable activation of a Kerr frequency comb on a Brillouin laser or cascaded Brillouin laser by adjusting the acoustic detuning.