Defective Soliton Crystal Microcomb in Silicon Nitride Microresonator

In our work, defective soliton crystals were observed for the first time in silicon nitride microresonators, and their generation dynamics caused by continuous-wave background and mode crossing conditions were numerically simulated. Extended background waves are incorporated into the soliton waveform circulating in the resonator, increasing or decreasing the efficiency of comb formation. A greater number of solitons emerge from the chaos due to the mode crossing, and the thermal stability of the soliton crystal is improved. The spectrum produced by the interference between solitons has a flat top in the C-band, and the conversion efficiency can reach ~10%. By introducing the time-varying local dispersion into the perturbed Lugiato-Lefever equation for modeling, the simulation results verify that the defective soliton crystal is a steady-state solution. This result will facilitate meeting more applications of defective soliton crystals in integrated photonic systems.