Ultra High-Q tunable microring resonators enabled by slow light
Abstract
High-Q nanophotonic resonators are crucial for many applications in classical and quantum optical processing, communication, sensing, and more. We achieve ultra-high quality factors by preparing a highly transparent and strongly dispersive medium within a resonator, causing a reduction in the group velocity that leads to a nearly three order of magnitude increase in the quality factor. We implement this via spectral hole burning in erbium-doped thin-film lithium niobate microring resonators, and show Q-factors exceeding . Additionally, we show that the interplay between the spectrally narrowed resonance and the broader bare resonance produces a Fano lineshape, which we dynamically control via electro-optic tuning. Finally, we present a theoretical model for our experimentally observed resonator linewidths, which are not well-described by the standard Bloch equations. Our results show a dramatic reduction in the erbium dephasing rate under a strong optical drive, leading to much narrower linewidths than would otherwise be expected given the large circulating intensity in the resonator.
Keywords
Cite
@article{arxiv.2504.19465,
title = {Ultra High-Q tunable microring resonators enabled by slow light},
author = {Priyash Barya and Ashwith Prabhu and Laura Heller and Edmond Chow and Elizabeth A. Goldschmidt},
journal= {arXiv preprint arXiv:2504.19465},
year = {2025}
}