Optical Kerr nonlinearity of dielectric nanohole array metasurface in proximity to anapole state

Abstract

Metasurfaces have attracted a great deal of attention from researchers due to their prominent optical properties. In particular, metasurfaces may consist of structures possessing optical anapole resonances with strong field confinement and substantially suppressed scattering. As a result, such nanostructures display enhanced nonlinear optical properties. In this paper by means of three-dimensional finite-difference time-domain simulations, the ability of anapole modes in high-index dielectric metasurfaces with circular nanopores is shown. In the vicinity of the anapole state, the effective optical Kerr nonlinearity increases by orders of magnitude. Simultaneously, the optical transmission of the metasurface can reach high values up to unity.

Possibility of Anapole State in Dielectric Nanohole Array Metasurfaces with Different Hole Shapes

“…These energy distributions are like those obtained for the circular nanohole arrays in Ref. [2]. The lattice elements of the square and octagonal shapes of the nanoholes have approximately two times larger electric energy enhancement near the edges of the pore than that of the hexagonal shape.…”

“…As shown in [2] by the multipole decomposition of scattering cross sections, for the specific geometric parameters of the circular nanohole array metasurface the maximum of the dipole electric toroidal moment is observed. This peak coincides with the minimum of the total scattering and can be illustrated by the double toroidal distribution of electric field energy.…”

“…Typically, the anapole states are observed in standalone dielectric nanoobjects (disks, spheres, cuboids etc.). Recently, high-index dielectric metasurfaces with circular nanopores were shown by the three-dimensional finite-difference time-domain (FDTD) simulations to possess the anapole state resulting in the effective optical Kerr nonlinearity increase by orders of magnitude [2]. This metasurface can be realized as a freestanding dielectric metasurface (membrane) that can be elaborated now for visible and near-infrared ranges [3,4].…”

“…Simultaneously, the total scattering cross section C sca tot and the electric dipole cross section C sca p have minima at λ=1034 nm that is the scattering from the lattice element is suppressed. The description of the decomposition moments and the procedure is given in [2]. All the spectra are very similar.…”

Tailoring the resonant modes in liquid crystal based all-dielectric metasurfaces

“…In dielectric metasurfaces anapole states are formed as a result of destructive interference between electric dipole and toroidal dipoles 9,37,38 giving rise to highly localised fields within the dielectric structures. Anapoles exhibit high Q-factors 39 and tailoring the anapoles give rise to unprecedented applications in sensing 40,41 , non-radiative waveguides 42 , wireless power transfer 43 , high harmonic generation 44 and non-linear optical responses 45 . Further, perfectly transmitting hybrid anapoles (HA's) are also observed recently in high refractive index dielectric structures formed due to the destructive interference between all possible multipoles with their toroidal counterparts 46 .…”