Study on the Filter Integrated with High Transmission and Ultra-Wideband Electromagnetic Shielding Function in the View of Surface Plasmon

The generation of a strong electromagnetic weapon requires the electromagnetic protection performance of the photoelectric system, including the high shielding and ultra-wideband protection characteristics against strong electromagnetic attacks and superhigh infrared transmittance. This article aims to excite surface plasmons by etching a subwavelength circular structure array run through a metal film. At the same time, the local field enhancement effect based on surface plasmons is used to tune specific wavelengths of light, achieving the goal of enhancing the optical transmission effect. Ulteriorly, the amplitude and position of the infrared response peak are controlled by optimizing the structural geometric parameters to achieve filtering effects in different wavebands. Furthermore, through the inversion calculation of the transmission spectrum of the circle array structure in the visible light band, the different colors of its surface under different parameters can correspond one-to-one to its performance, so as to intuitively identify different filter types and their performance. Meanwhile, the remaining metal film after etching off the circle array structure region constitutes an ultra-wideband shielding layer as a continuous conductor, achieving a shielding efficiency of more than 45 dB in the radar band (1–18 GHz). It is worth noting that the cascaded theory combines ultra-thin metal films with thick substrates to solve the problem of software running for long periods of time and under high loads during the simulation of light propagation. This scheme greatly reduces the error between simulation and practical application.