2018/02/05 by Zhiyuan Fan, Maxim R. Shcherbakov, Fan, Zhiyuan +7 · 5 citations
Engineering · Materials Science · Physics and Astronomy · #Advanced Antenna and Metasurface Technologies #Broadband #Computer science #Curved mirror #Diffraction #Diffraction efficiency #Diffraction grating #FOS: Physical sciences #Grating #Metamaterial #Metamaterials and Metasurfaces Applications #Optics #Optics (physics.optics) #Physics #Planar #Plasmonic and Surface Plasmon Research #Sawtooth wave #Telecommunications #Wavelength #physics.optics
paper · pdf · doi:10.48550/arxiv.1802.01269
published in arXiv (Cornell University) (Cornell University) · 18 pages, 4 figures
arxiv created 2018/02/05 · openalex publication_date 2018/02/05 · arxiv updated 2018/02/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
One highly desirable function of a diffraction grating is its ability to deflect incident light into a specific diffraction order with near-perfect efficiency. While such asymmetry can be achieved in a variety of ways, e.g., by using a sawtooth (blazed) geometry, a recently emerged approach is to use a planar metagrating comprised of designer multi-resonant periodic units (metamolecules). Here we demonstrate that a bianisotropic unit cell supporting four resonances interfering in the far field can be used as a building block for achieving the prefect deflection. A coupled mode analysis shows that these modes provide a small number of orthogonal electromagnetic radiation patterns that are needed to suppress transmission/reflection into all but one diffraction order. Bianisotropy caused by a mirror symmetry breaking enables a normally incident wave to excite, through near-field couplings, two otherwise "dark" resonant modes. We design and experimentally realize bianisotropic metamolecules which are sub-wavelength in all three dimensions, and whose optical properties are desensitized to fabrication imperfections by their geometric simplicity. We show that optical beams tightly focused onto the metagratings with just a few unit cells can also be asymmetrically deflected with high efficiency, paving the way for compact broadband optical devices.