Direct Observation of Switching-Wave Dynamics in 20 GHz Normal Dispersion Spiral Microresonators
Abstract
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 × 106, 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.
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BibTeX
@misc{le2026direct,
title = {{Direct Observation of Switching-Wave Dynamics in 20 GHz Normal Dispersion Spiral Microresonators}},
author = {Van Doan Le and Julien Fatome and Erwan Lucas},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.31475},
eprint = {2609.31475},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.31475},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Direct Observation of Switching-Wave Dynamics in 20 GHz Normal Dispersion Spiral Microresonators
AU - Van Doan Le
AU - Julien Fatome
AU - Erwan Lucas
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2609.31475
UR - https://arxiv.org/abs/2609.31475
AB - 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 × 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.
ER -