LAUSR

We develop an analytical model to understand the generation of tunable free spectral range frequency comb (FC) and composite FC using two competing phenomena, namely nondegenerate four-wave mixing (FWM) and intensity-dependent modulation instability (MI) in dual-pumped micro-resonator configurations. Our analytical approach is based on the popular four-wave model. The MI rate at the onset, corresponding to the most susceptible frequency component that conditionally accompanies threshold-less comb generation in case of dual pump, is derived. Based on the analytical model, the mutual interplay of nondegenerate FWM and threshold intensity-dependent MI is investigated in detail for the comb generation process, and their regions of operations are clearly demarcated. The proposed analytical model provides a deterministic and quick estimation of micro-resonator parameters for generating a variety of FCs while avoiding the computationally intensive route of solving the Lugiato–Lefever equation. A close agreement between the analytical and numerical simulation is found.