Study of Extinction Characteristics of Au-Ag Nanosphere Periodic Array

摘要

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.