Abstract

Dielectric nanoparticle-based metasurfaces, such as Si, can support both electric and magnetic Mie resonances. The coupling of Mie resonances of scatterers and in-plane scattered light in periodic arrays result in Mie surface lattice resonances (SLRs), inspiring novel optical phenomenon and unique functionalities. An example, the spectral overlap of electric dipole (ED) and magnetic dipole (MD) with equal intensities generates a scattering directionality, so-called lattice Kerker effect [1], bringing zero transmission/reflection and perfect absorption. However, the extrinsic losses such as defects and surface roughness are usually brought from the nanofabrication process. Rapid thermal annealing (RTA) has been reported to be an effective way to improve the optical performance of nanostructures through the reduction of the defects [2-3]. The present work demonstrates a robust way of refining the sputter-made Si metasurfaces by post-annealing using RTA. We design the Si nanodisk arrays to sustain sharp ED and MD-SLRs and show the lattice Kerker effect after RTA where the near-zero reflectance and near-perfect absorptance appear. Simulation was used to give the physical interpretation.

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