Achieving power transmission enhancement by using nano-rings made of silver spheres

In this letter, we propose the employment of nano-rings made of silver spheres, to enhance the transmission through a subwavelength aperture drilled in a metallic screen at optical frequencies. We show that the increase in the transmission is due to the excitation of a strong magnetic resonance in close proximity of the aperture. Compared to similar configurations presented in the literature, the proposed layout allows us to significantly reduce the size of the setup. The effectiveness of the approach is demonstrated through proper full-wave simulations, taking into account material dispersion and losses. In addition, it is shown how the nano-ring response can be tuned by embedding the structure in a host material, doped with liquid crystals