A theoretical study of optically enhanced transmission characteristics of subwavelength metal Y-shaped arrays and its application on refractive index sensor

Abstract

In this paper, the electric field distributions and transmission characteristics of subwavelength Y-shaped metal hole arrays are studied by using the finite element method (FEM). The results show that the Y-shaped metal hole arrays can achieve light-enhanced transmission in the subwavelength region, and the electric field distributions around the corners are stronger. When the energy of surface plasmon polaritons (SPPs) and local surface plasmon (LSP) are similar, it is more favorable for the transmission of metal nanohole structure. In addition, the influence of the inclined angle, thickness, width, and period on the transmission of this structure is also discussed. The effect of the inclined angle on the transmission characteristics is particularly obvious. As the angle increases, the transmittance increases from 0.558 to 0.628 at the wavelength of 0.67 μm, and the transmittance of 0.289 at the wavelength of 1.08 μm increases to 0.840 at 1.17 μm. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity (S) as high as 900 nm/RIU, and the corresponding sensing resolution is 2.22 × 10−4 RIU. These results would be helpful in designing the refractive index sensor of high-sensitivity and band-pass filters, and have guiding significance for biological sensor applications.