Single envelope equation modeling of multi-octave comb arrays in microresonators with quadratic and cubic nonlinearities

摘要

We numerically study, by means of the single envelope equation, the generation of optical frequency combs\udranging from the visible to the mid-infrared spectral regions in resonators with quadratic and cubic nonlinearities.\udPhase-matched quadratic wave-mixing processes among the comb lines can be activated by low-power continuous\udwave pumping in the near infrared of a radially poled lithium niobate whispering gallery resonator. We examine\udboth separate and coexisting intracavity doubly resonant second-harmonic generation and parametric oscillation\udprocesses and find that modulation instabilities may lead to the formation of coupled comb arrays extending over\udmultiple octaves. In the temporal domain, the frequency combs may correspond to pulse trains or even to a single\udpulse circulating in the cavity.