Asymmetric optical transmission through periodic metallic hemisphere arrays on the transparent substrates

Abstract

Asymmetric optical transmission is useful in various fields such as electromagnetic shielding, photovoltaic devices, and optical diodes owing to its directional selectivity for light. This work theoretically investigates asymmetric optical transmission by the periodic metallic hemisphere arrays on the transparent substrates. It is found that the formation of asymmetric optical transmission can be attributed to two aspects: the difference in the driving electric field and the first-order diffraction of the arrays. The maximum asymmetric optical transmission results from the match between the resonance wavelength of the arrays and the cut-off wavelength of the first-order diffraction inside the substrates. The bandwidth of asymmetric optical transmission is determined by the cut-off wavelength of the first-order diffraction inside the substrates. In addition, the effects of the structural parameters, including the radius of the metallic hemisphere and the material of the transparent substrate, on the maximum asymmetric optical transmission and the bandwidth are studied. This work provides design guidelines for practical devices to apply asymmetric optical transmission.