Engineered FWHM enhancement in plasmonic nanoresonators for multiplexer/demultiplexer in visible and NIR range

Abstract

Plasmonic multiplexer/demultiplexer (M/D) device is a basic element in optical integrated circuits. In this regard, we report on: (i) Deriving exact analytical coupled-mode theory relations, when a plasmonic layer is placed on ‎dielectrics with up to six plasmons excitation frequencies; (ii) How to alter reduce the discrepancy between the analytical and the finite difference time domain ‎results at the visible and near-infrared range, correctly identifying the point that the plasmons start to damp. A novel plasmonic disk resonator-based drop filter with a small size and high-quality factor is proposed to design two-channel, four-channel and six-channel M/Ds. According to the simulation results, for two-channel, four-channel, and six-channel M/Ds the minimum FWHM values of 6.44 nm, 5.5 nm, and 7 nm, the maximum quality factors of 126, 147.6, and 90.5, and the minimum cross-talks of − 36.1 dB, − 46 dB, and − 41 dB are obtained. Our achievements are significant because the new model (I) Overcomes the limitations in surface plasmons dispersion observed from the 2D classical ‎model; (II) Describes the proper behavior of plasmons in the presence of plasmonic multiplexer; (III) Pave a way of calculating accurate theoretical current in plasmonic filters by providing ‎accurate plasmonic content.