Abstract
Dielectric microcavities with quality factors (Q-factors) in the thousands to billions markedly enhance light–matter interactions, with applications spanning high-efficiency on-chip lasing, frequency comb generation and modulation and sensitive molecular detection. However, as the dimensions of dielectric cavities are reduced to subwavelength scales, their resonant modes begin to scatter light into many spatial channels. Such enhanced scattering is a powerful tool for light manipulation, but also leads to high radiative loss rates and commensurately low Q-factors, generally of order ten. Here, we describe and experimentally demonstrate a strategy for the generation of high Q-factor resonances in subwavelength-thick phase gradient metasurfaces. By including subtle structural perturbations in individual metasurface elements, resonances are created that weakly couple free-space light into otherwise bound and spatially localized modes. Our metasurface can achieve Q-factors >2,500 while beam steering light to particular directions. High-Q beam splitters are also demonstrated. With high-Q metasurfaces, the optical transfer function, near-field intensity and resonant line shape can all be rationally designed, providing a foundation for efficient, free-space-reconfigurable and nonlinear nanophotonics.
Original language | English (US) |
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Pages (from-to) | 956-961 |
Number of pages | 6 |
Journal | Nature nanotechnology |
Volume | 15 |
Issue number | 11 |
DOIs | |
State | Published - Nov 1 2020 |
Funding
We thank R. Tiberio and U. Raghuram for helpful discussions regarding fabrication. This work was supported by PECASE (grant no. FA9550-15-10006) and NSF EFRI (grant no. 1641109). The device fabrication, performed in part by J.D., was supported by the DOE ‘Photonics at Thermodynamic Limits’ Energy Frontier Research Center under grant no. DE-SC0019140. J.v.d.G, J.-H.S. and M.L.B. acknowledge funding from an individual investigator grant from AFOSR (no. FA9550-18-1-0323). Part of this work was performed at the Stanford Nano Shared Facilities and Stanford Nanofabrication Facilities, which are supported by the National Science Foundation and National Nanotechnology Coordinated Infrastructure under award no. ECCS-1542152.
ASJC Scopus subject areas
- Bioengineering
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- General Materials Science
- Condensed Matter Physics
- Electrical and Electronic Engineering