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Resonant periodic nanostructures provide perfect reflection across small or large spectral bandwidths depending on the choice of materials and design parameters. This effect has been known for decades, observed theoretically and experimentally via one-dimensional and two-dimensional structures commonly known as resonant gratings, metamaterials, and metasurfaces. The physical cause of this extraordinary phenomenon is guided-mode resonance mediated by lateral Bloch modes excited by evanescent diffraction orders in the subwavelength regime. In recent years, hundreds of papers have declared Fabry-Perot or Mie resonance to be the basis of the perfect reflection possessed by periodic metasurfaces. Treating a simple one-dimensional cylindrical-rod lattice, here we show clearly and unambiguously that Mie resonance does not cause perfect reflection. In fact, the spectral placement of the Bloch-mode-mediated zero-order reflectance is primarily controlled by the lattice period by way of its direct effect on the homogenized effective-medium refractive index of the lattice. In general, perfect reflection appears away from Mie resonance. However, when the lateral leaky-mode field profiles approach the isolated-particle Mie field profiles, the resonance locus tends towards the Mie resonance wavelength. The fact that the lattice fields“remember” the isolated particle fields is referred here as“Mie modal memory.” On erasure of the Mie memory by an index-matched sublayer, we show that perfect reflection survives with the resonance locus approaching the homogenized effective-medium waveguide locus. The results presented here will aid in clarifying the physical basis of general resonant photonic lattices.
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Mie‐Resonant Metasurfaces with Controlled Silicon Oxidation in Electron‐Beam Deposition
Abstract Electron‐beam deposition stands as a versatile technique utilized for the accurate and controlled thin‐film deposition of a wide range of materials that readily undergo evaporation. However, silicon, a commonly used material, is prone to oxidation during the deposition process because of the presence of water vapors and oxygen in the chamber. To overcome this challenge, a tailored approach is developed that involves controlling the deposition conditions, including the base pressure in the chamber and the deposition rate. Silicon oxidation is successfully overcome, and this results in achieving refractive index values comparable to those obtained with alternative deposition methods for amorphous silicon. The research shows that the deposition conditions can be utilized effectively to tune the refractive index, providing flexibility in achieving the desired optical properties. It is demonstrated that Mie‐resonant metasurfaces exhibit strong collective resonances, driven by the coherent coupling of Mie modes within the periodic nanoantenna lattice, as evidenced by distinct spectral features in the scattering response. These resonances are observed to be highly tunable, with spectral shifts corresponding to controlled variations in the electron‐beam deposition parameters and silicon oxidation. The approach enables silicon deposition for metasurfaces, which presents exciting possibilities for tailoring and designing advanced nanostructures with unique optical characteristics.
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- Award ID(s):
- 2418519
- PAR ID:
- 10640995
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 12
- Issue:
- 14
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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