Abstract
Abstract Gradient metasurfaces have been extensively applied in the unprecedented control of light beams over thin optical components. However, these metasurfaces suffer from low efficiency when bending light through large angles and high fabrication demand when it requires fine discretion. In this work, we investigate all-dielectric metagratings based on the generalized Kerker effect induced by interference between Mie-type resonances. It allows extraordinary optical diffraction for beam steering through ultralarge angles. The coupling inside and between the lattices in the metagrating can be used to tune the excited states of the electric and magnetic resonances, including both the fundamental dipoles and high-order multipoles, leading to an ideal asymmetrical scattering pattern that redistributes the energy between the diffraction channels as required. The quadrupole and hexadecapole not only significantly enhance the working efficiency but also enable distinctive possibilities for wave manipulation that cannot be reached by dipoles. Utilizing a thin array of silicon rods, large-angle negative refraction and reflection are realized with almost unity efficiency under both transverse magnetic and transverse electric polarization. Compared with conventional metasurfaces, such an all-dielectric metagrating has the merits of high flexibility, high efficiency, and low fabrication requirements. The coupling and interactions among the multipoles may serve as a foundation for various forms of on-chip optical wave control.
Highlights
The rapid development of exotic metamaterials has enabled the unprecedented manipulation of electromagnetic waves which cannot be attained by natural materials [1, 2]
The promising wave steering is realized by using the metagrating profiles, the ability of dielectric rods is obviously not limited to the several functions demonstrated
A rod grating can work in transmission or reflection mode and the working performance can be sensitive or robust to the parameters
Summary
The rapid development of exotic metamaterials has enabled the unprecedented manipulation of electromagnetic waves which cannot be attained by natural materials [1, 2]. It has been shown that the interference between Mie resonances in periodic structures with defined multipolar characteristics is a novel way to form scattering patterns, which is known as the generalized Kerker effect [38] This designed scattering pattern can be used to choose the diffraction order and eliminate all the unwanted channels. We analytically investigate the efficient manipulation of waves through large angles, as induced by the generalized Kerker effect inside periodic high-index nanoparticles. Efficiencies close to 100% for the large-angle negative reflection and refraction of incident waves are demonstrated for both transverse magnetic (TM) and transverse electric (TE) polarization These low-loss all-dielectric structures may stimulate the design of compact optical components with a low profile and high efficiency
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