Simultaneous low-pass and high-pass filtering based on a metal-insulator-metal structure with SPPs

In this paper, a metal-insulator-metal (MIM) structure with dual output channels based on SPPs is proposed and discussed, which can realize both low-pass and high-pass filtering effects simultaneously. The straight waveguide with a thin metal silver baffle outputs low-pass filtering and the other waveguide composed of multiple cavities outputs high-pass filtering. After optimizing the structural parameters, relatively ideal low-pass and high-pass filtering effects are achieved, and the edge steepnesses of low-pass and high-pass output channels are −3.14 × 10⁻³/nm and 4.54 × 10⁻³/nm, respectively. In addition, in order to adjust the filtering effects, standard optical glass BK-7 with Kerr effect is utilized in the structure. The adjustment sensitivities of low-pass and high-pass output channels caused by external light irradiance are 11.7 nm μm²/W and 13.9 nm μm²/W, respectively. The dual channels filter with simultaneous low-pass and high-pass filtering provides novel conceptions for the construction of filters, and may have broad applications in the field of optical information processing.