<i>Q</i> Factors Exceeding 10<sup>4</sup> in Wavelength-to-Subwavelength-Scale Free-Space Resonators with Dual Asymmetry Control.
basic_science · Level V
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- Record sourced from PubMed, PMID 42281364.
- Also identified by DOI 10.1021/acs.nanolett.6c02042.
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Abstract
Free-space-addressable optical resonators with high quality factors (<i>Q</i>) and wavelength-to-subwavelength mode volumes (<i>V</i><sub>m</sub>) enhance light-matter interactions in sensing, nonlinear optics, and quantum photonics. However, experimental <i>Q</i> factors in this mode volume regime remain limited to ∼10<sup>3</sup> because existing asymmetry-driven designs couple geometric and optical perturbation components, constraining access to high-<i>Q</i> regimes. Here, we show that independently tuning these two asymmetry axes unlocks a biaxial radiative landscape with iso-<i>Q</i> contours connecting geometrically and optically distinct perturbations of equivalent <i>Q</i>. We demonstrate this framework in very-large-scale-integrated Si nanoantenna pixel (VINPix) resonators with 35-150 nm out-of-plane perturbations of amorphous Si, SiN<sub><i>x</i></sub>, and SiO<sub>2</sub>. Experimentally, we achieve <i>Q</i> up to 76 000 at <i>V</i><sub>m</sub> of ∼1.7 λ<sub>0</sub><sup>3</sup><i>n</i><sub>eff</sub><sup>-3</sup> across arrays of >80 resonators in water. Computationally, slotted VINPix resonators reach <i>Q</i> of >10<sup>6</sup> at <i>V</i><sub>m</sub> of ∼0.2 λ<sub>0</sub><sup>3</sup><i>n</i><sub>eff</sub><sup>-3</sup>. This biaxial framework establishes a generalizable design strategy for ultrahigh-<i>Q</i> free-space nanophotonic resonators.