Implementing photonic-crystal resonator frequency combs in a photonics foundry

TL;DR

This paper demonstrates scalable fabrication of high-Q silicon-nitride photonic-crystal resonators on large wafers, enabling tunable optical parametric oscillators and soliton microcombs for advanced photonic applications.

Contribution

It introduces a scalable, foundry-compatible process for creating low-loss, high-Q photonic-crystal microresonators with complex nanostructures in silicon-nitride, enabling diverse nonlinear photonic sources.

Findings

Achieved intrinsic quality factor up to 1.2×10^7 in silicon-nitride resonators.

Demonstrated broad tunability of OPO frequency across the near-infrared.

Observed formation of soliton frequency combs through dispersion engineering.

Abstract

We explore an AIM Photonics silicon-nitride platform to fabricate photonic-crystal resonators for generating optical parametric oscillators (OPO) 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 nano-scale photonic-crystal structures. We demonstrate intrinsic microresonator quality factor up to 1.2*10^7 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 nanophotonics 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.