Controlling frequency distance between individual modes of dielectric resonator nanoantenna using uniaxial anisotropic materials

A technique to significantly shift down the resonant frequency of the higher order modes of a uniaxial anisotropic rectangular dielectric resonator nanoantenna (DRNA) without any considerable change in the resonant frequency of the fundamental mode is presented. The method aims to adjust the ratio of the resonant frequency of the higher order modes without changing the physical dimensions of DRA. This method can be used to adjust the frequency distance between the high-order and fundamental modes of the antenna. The performances of the method are numerically validated for different contrast values between the dielectric tensor entries.