Large area metasurfaces made with spherical silicon resonators
Pau Molet, Luz Karimé Gil-Herrera, Juan Luis Garcia-Pomar, Niccolò Caselli, Álvaro Blanco, Cefe López, Agustín Mihi. Nanophotonics. Received January 16, 2020; revised February 20, 2020; accepted February 22, 2020.
High-index dielectric nanostructures have emerged as an appealing complement to plasmonic nanostructures, offering similar light management capabilities at the nanoscale but free from the inherent optical losses. Despite the great interest in these all-dielectric architectures, their fabrication still requires cumbersome fabrication techniques that limit their implementation in many applications. Hence, the great interest in alternative scalable procedures. Among those, the fabrication of silicon spheres is at the forefront, with several routes available in the literature. However, the exploitation of the Mie modes sustained by these silicon resonators is limited over large areas by polydispersity or a lack of long-range order. Here, we present an all-dielectric metamaterial fabricated with a low cost and highly scalable technique: a combination of soft imprinting nanolithography and chemical vapor deposition. The resulting all-dielectric metasurface is composed of an array of silicon hemispheres on top of a high refractive index dielectric substrate. This architecture allows the exploitation of high-quality Mie resonances at a large scale due to the high monodispersity of the hemispheres organized in a single crystal two-dimensional lattice. The optical response of the metasurface can be engineered by the design parameters of the nanoimprinted structure. We further demonstrate the potential of this platform to enhance light emission by coupling dye molecules to the sustained Mie resonances and measuring both an eight-fold amplified signal and a triple lifetime reduction.
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