Resonant coupler delivers 450 nm bandwidth SiN soliton microcomb at 98 GHz spacing with tens of mW pump power
The arXiv preprint demonstrates a resonant-coupler-enabled SiN microcomb that combines 450 nm bandwidth near 1 μm with 98 GHz spacing at low pump power. This removes a key barrier to compact, coherent sources for biological-window metrology. Evidence rests on a single device demonstration; replication across multiple chips and environments is still required.
The device uses a resonant coupler to boost pump delivery into the nonlinear Si3N4 ring, lowering the threshold for broadband soliton formation. Experiments showed reliable access to the single-soliton state across the biological window without external thermal control, directly addressing the usual trade-off between spectral width and comb spacing. Pump powers remained below 50 mW on-chip while delivering coherent lines suitable for spectroscopy and imaging.
Prior microcomb work required either high pump powers or suffered narrow bandwidth when targeting ~1 μm wavelengths. The coupler approach decouples pump efficiency from dispersion engineering, allowing both broad coverage and dense lines. This matters for optical coherence tomography and diffuse spectroscopy where water absorption and scattering demand precisely this spectral region.
Next steps include packaging the coupler-resonator chip with integrated lasers and testing in benchtop biomedical prototypes. If power and stability hold under real-world thermal fluctuations, the architecture could reach clinical imaging systems within three years.
Luo et al.: Packaged versions will demonstrate stable OCT imaging in tissue phantoms at 1 mm depth within 18 months.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2610.12603)
- [2]Supporting Source(https://www.nature.com/articles/s41586-022-05121-3)