Study of Extinction Characteristics of Au–Ag Nanosphere Periodic Array

Abstract

In order to study the extinction characteristics of the periodic structures of Au and Ag nanospheres, an Au–Ag nanosphere periodic array structure has been established. Firstly, the geometry structure and research methods of Au–Ag structure are introduced. Secondly, the LSPR absorption spectra of Au–Ag nanospheres periodic array and Au and Ag nanospheres periodic array were compared by the finite difference time domain method. Then, the simulation and analysis of periodic array of Au–Ag nanospheres with different sizes and spacings are carried out. Finally, the Au–Ag nanosphere periodic array structures in different media environments are simulated and analyzed, and the refractive index sensitivity is obtained. The simulation results show that Au–Ag nanoparticles periodic array structure has two LSPR absorption peaks, and the two peaks position relative to the separate Au and Ag nanoparticles periodic arrays of LSPR absorption peak showed blueshift; in the same spacing condition, with the increase of radius r, the absorption peak wavelength of the double peak showed redshift firstly and then blueshift; when the radius r is constant, the LSPR peak wavelength showed redshift with the increase of the spacing L; owing to Au nanospheres contribution in Au–Ag nanoparticles, the refraction absorption peak with the refractive index of the fitting rate sensitivity is 101.11 nm/RIU, refractive index sensitivity of 82.985 nm/RIU is higher than that of Au nanoparticles periodic array alone; and the contribution by Ag nanospheres in Au–Ag nanoparticles resulted in refraction absorption peak with the refractive index of the fitting rate sensitivity of 130.3 nm/RIU is lower than that of Ag nanoparticles periodic array of individual Refractive index sensitivity 154.23 nm/RIU. The structure basically meets the requirements of optical sensing accuracy and can be applied to filters.