Active nonlocal metasurfaces

Stephanie C. Malek, Adam C. Overvig, Sajan Shrestha, Nanfang Yu

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

Actively tunable and reconfigurable wavefront shaping by optical metasurfaces poses a significant technical challenge often requiring unconventional materials engineering and nanofabrication. Most wavefront-shaping metasurfaces can be considered "local"in that their operation depends on the responses of individual meta-units. In contrast, "nonlocal"metasurfaces function based on the modes supported by many adjacent meta-units, resulting in sharp spectral features but typically no spatial control of the outgoing wavefront. Recently, nonlocal metasurfaces based on quasi-bound states in the continuum have been shown to produce designer wavefronts only across the narrow bandwidth of the supported Fano resonance. Here, we leverage the enhanced light-matter interactions associated with sharp Fano resonances to explore the active modulation of optical spectra and wavefronts by refractive-index tuning and mechanical stretching. We experimentally demonstrate proof-of-principle thermo-optically tuned nonlocal metasurfaces made of silicon and numerically demonstrate nonlocal metasurfaces that thermo-optically switch between distinct wavefront shapes. This meta-optics platform for thermally reconfigurable wavefront shaping requires neither unusual materials and fabrication nor active control of individual meta-units.

Original languageEnglish
Pages (from-to)655-665
Number of pages11
JournalNanophotonics
Volume10
Issue number1
DOIs
StatePublished - 1 Jan 2021

Keywords

  • metasurface
  • nonlocal
  • optical modulator
  • quasi-bound states in the continuum

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