Implementing photonic-crystal resonator frequency combs in a photonic foundry

We explore an AIM Photonics silicon nitride platform to fabricate photonic-crystal resonators (PhCRs) for generating optical parametric oscillators (OPOs) and soliton microcombs. Our approach leverages the scalability and fine feature size of silicon nitride processing on large-scale silicon wafers to achieve low-loss, high-Q microresonators, functionalized by nanoscale photonic-crystal structures. We demonstrate an intrinsic microresonator quality factor up to 1.2 × 10⁷ with complete foundry fabrication on 300 mm silicon, a 700 nm thick silicon nitride device layer, and inclusion of complex nanophotonics. These features enable a host of nonlinear nanophotonic sources on the platform, including OPOs, microcombs, parametric amplifiers, squeezed-light generators, and single-photon sources. By fine-tuning the photonic-crystal design parameters, we achieve broad tunability in the frequency of the OPO output, spanning a significant portion of the near-infrared. Additionally, we observe the formation of soliton frequency combs, enabled by the precise dispersion engineering of the microresonators. These results highlight the potential of widely accessible, photolithographically patterned, silicon nitride photonics to enable wide access to and complex integration of frequency comb sources, with applications in spectroscopy, metrology, and communications.