title: Optical 'magnetic mirror' metasurfaces using interference between Fabry-Pérot cavity resonances in coaxial apertures.
abstract: Here we propose and computationally demonstrate a quasi-planar metasurface consisting of arrays of pairs of concentric coaxial apertures in a metallic film. The structure relies on destructive interference between Fabry-Pérot modes excited in each aperture at resonance producing transmitted fields that interfere destructively leading to suppressed transmission. Conversely, we show that in the case of a perfect conductor, near-perfect, broadband reflection can be achieved with zero phase change in the electric field and a variation of 2π on passing through the coincident resonances. Extending the concept to shorter wavelengths, we show that mirrors exhibiting close to a 2π phase excursion, albeit with a reduction in the amplitude reflection coefficient at resonance and a lower Q, can be also achieved. Structures such as these can be used to enhance light-matter interactions at surfaces and act as high impedance ground planes for antenna applications.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Ranjith
authors.initials: R
authors.lastname: Rajasekharan
authors.affiliation: School of Physics, The University of Melbourne, Victoria, 3010, Australia.
authors.forename: Ann
authors.initials: A
authors.lastname: Roberts