2026-10-14T04:49:52Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34024968 2026-09-29T16:00:45Z category_37476 portal_1023 item_type_12 month_year_09_2026

Direct Observation of Switching-Wave Dynamics in 20 GHz Normal Dispersion Spiral Microresonators Van Doan Le (18115383) Julien Fatome (4584598) Erwan Lucas (4180180) Physics (arXiv) physics.optics (arXiv) Integrated Kerr frequency combs are powerful tools for microwave photonics, spectroscopy, and optical communications. While traditional architectures rely on the anomalous-dispersion regime, this typically requires thick, highly strained silicon nitride layers that complicate standard CMOS-foundry fabrication. Thinner layers circumvent these fabrication constraints but yield normal-dispersion microcombs that generally require specific trigger mechanisms, such as deterministic seeding, due to the absence of spontaneous modulational instability. Here, we demonstrate the generation of a 20 GHz microcomb in the normal-dispersion regime, driven by a synchronized dual-pump scheme via electro-optic sidebands modulation. The platform leverages an Archimedean spiral geometry on a foundry-compatible, 350 nm-thin SiN platform. By employing adiabatic curvature engineering, the resonator balances a compact footprint with an intrinsic quality factor exceeding $7 \times 10^6$, while effectively eliminating avoided mode crossings with higher order modes. This strong-dispersion architecture yields a low-repetition-rate microcomb featuring high power-per-line and picosecond-scale temporal profile, which enables the direct optical sampling and characterization of the out-coupled switching wave waveforms. The measured dynamics across a range of pump desynchronizations demonstrate excellent agreement with simulations. Our work establishes a scalable, strategy for footprint-efficient normal-dispersion microcomb generation at microwave frequencies, with potential for scaling to other wavelength ranges. 2026-09-25T00:00:00Z Text Preprint 10.48550/arXiv.2609.31475 https://figshare.com/articles/preprint/Direct_Observation_of_Switching-Wave_Dynamics_in_20_GHz_Normal_Dispersion_Spiral_Microresonators/34024968 CC0