Nanoscale Fabry–Pérot Interferometer using channel plasmon-polaritons in triangular metallic grooves

In this letter, we demonstrate the possibility of an effective nanoscale Fabry–Pérot interferometer in a subwavelength plasmonic waveguide in the form of a triangular groove on a metal surface, guiding channel plasmon-polaritons. The resonant cavity is formed by two semitransparent metal membranes (mirrors) placed into the groove. Effective filtering effect of the cavity is demonstrated, resulting in single-mode output from the cavity. Typical quality factor for the cavity of the resonant length is determined to be $Q\sim 100$ for the silver-vacuum structure with the 30° groove angle. Possible ways of increasing this factor are discussed.