Enhanced plasmonic band-pass filter with symmetric dual side-coupled nanodisk resonators

Abstract

A plasmonic band-pass filter with symmetric dual side-coupled nanodisk resonators in metal-insulator-metal system is proposed. Compared with the single side-coupled nanodisk resonator structure, the new structure has better transmission response due to the superposition of the outgoing-wave fields' amplitudes of the two resonators. The accurate transmission expression is provided based on the temporal coupled mode theory, and the dynamic transmission response is studied by finite difference time domain method. It is indicated that the transmission characteristics of the symmetric dual nanodisk resonator structure is sensitive to the refractive index of the nanodisk resonators and geometrical parameters. Moreover, the optimum transmission at the wavelengths of 1310 nm and 1550 nm can reach up to 90.8% and 86.2%, with the relative full width at half-maximum of 35 nm and 42 nm, which are better than the results reported in recent literatures. The filter we proposed has important potential applications on plasmonic nanostructures in highly integrated optical circuits and optical information processing.