Double-Frequency Filter Based on Coupling of Cavity Modes and Surface Plasmon Polaritons

In order to achieve a double-frequency filter, we design a sandwiched structure with a dual-prism total reflection configuration. The sandwiched structure consists of one metal layer and two same media layers. The transmission properties are studied through the standard transfer matrix method. Such system can form two hybrid cavity-surface plasmon-polariton modes. The coupling of the two hybrid modes results in resonance tunneling effect and mode splitting. Mode splitting leads to the coupled double peaks. The difference of double-peak frequencies can be adjusted through changing the metal thickness, and the position of double peaks can be also tunable through changing incidence direction. Such system can be used in designing double-frequency filters and terahertz emission devices.