Pure quartic solitons in dispersion-engineered aluminum nitride micro-cavities

Pure quartic soliton (PQS) is a new class of solitons demonstrated in recent years and provides innovations in nonlinear optics and its applications. Generating PQSs in micro-cavities offers a novel way to achieve coherent microcombs, presenting a promising application potential. Here we numerically investigate the PQS generation in a dispersion-engineered aluminum nitride (AlN) micro-cavity. To support PQS, a well-designed shallow-trench waveguide structure is adopted, which is feasible to be fabricated. The structure exhibits a dominant fourth-order dispersion reaching up to -5.35x10(-3) ps(4)/km. PQSs can be generated in this AlN micro-cavity in the presence of all-order-dispersion and stimulated Raman scattering. Spectral recoil and soliton self-frequency shift are observed in the PQS spectrum. Furthermore, we find that due to the narrow Raman gain spectrum of crystalline AlN, the PQS evolves directly to chaos rather than turning into a breather. The threshold pump power with which the PQS turns into chaos is also theoretically calculated, which squares with the simulation results. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Pure quartic solitons (PQS) have been demonstrated as a new class of solitons in recent years, offering innovations in nonlinear optics and potential applications. Numerical investigation in a dispersion-engineered aluminum nitride (AlN) micro-cavity shows that PQS can be generated with the support of a well-designed shallow-trench waveguide structure. Spectral recoil and soliton self-frequency shift are observed in the PQS spectrum.