Numerical analysis of SPP excitation process on metal periodic array structure

Abstract

A new method for polarization dependence analysis of periodic nanostructured SERS substrates was proposed. The method combines the Fourier transform and the wave vector matching model of surface plasmon polariton (SPP). The periodic nanostructured SERS substrate was sensitive to the polarization Angle of incident light, which seriously affected the application of the substrate in practical detection. In this paper, based on the Drude model, the wave vector matching conditions of metal surface plasmas excited by incident light are studied. The compensation wave vector deviation coefficient η which characterizes the weakening degree of surface electric field intensity under different polarization angles of incident light is defined. The finite-difference time-domain (FDTD) and η -value analysis of one-dimensional and two-dimensional sinusoidal gratings are carried out respectively. Compared with the relationship curve obtained by the two methods, there is a negative correlation between the η -value curve and the maximum electric field intensity E_max curve of the grating surface. Moreover, the difference between the theoretical value of E_max and the simulation result is very small ( Δ <0.2). FDTD simulation and calculation results show that η -value can well describe the attenuation law of E_max of periodic nanostructured SERS substrate when the polarization angle of incident light changes. The method has simple analysis process and less computation. This method provides a fast and simple polarization correlation analysis method for SERS substrate design.