Wideband multimode optical parametric oscillation in a Kerr microresonator

Parametric oscillation in Kerr microresonators provides an attractive pathway for the generation of new optical frequencies in a low-power, small-footprint device. The frequency shift of the newly generated parametric sidebands is set by the phasematching of the underlying four-wave-mixing process, with the generation of large frequency shift sidebands typically placing exacting requirements on a resonator's dispersion profile. In practice, this limits the range of viable pump wavelengths, and ultimately the range of output frequencies. In this paper, we consider a multimode four-wave-mixing process in which the pump and sidebands propagate in different mode families of the resonator. We show that this multimode configuration yields a considerable relaxation in the phasematching requirements needed to generate large frequency shift parametric sidebands, allowing their formation even in resonators with strong second-order dispersion. Experimentally we use a magnesium-fluoride micro-disk resonator to demonstrate this multimode phasematching. By accessing different pump and sideband modes, four distinct multimode parametric processes generating frequency shifts between 118 and 216 THz are reported. The resulting separation between the two sidebands is almost three octaves. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Parametric oscillation in Kerr microresonators offers a promising method to generate new optical frequencies in a compact and low-power device. However, the generation of large frequency shift sidebands usually requires precise phasematching, which is limited by the resonator's dispersion profile. In this paper, we propose a multimode four-wave-mixing process that relaxes the phasematching requirements, allowing the formation of large frequency shift sidebands even in resonators with strong second-order dispersion. Experimental results using a magnesium-fluoride micro-disk resonator demonstrate the generation of four distinct multimode parametric processes with frequency shifts ranging from 118 to 216 THz, achieving a separation of almost three octaves between the two sidebands.