Plasmon-induced absorption and its applications for fast light and sensing based on double-stub resonators

We propose a double-stub resonator (DSR) end-coupled two metal-insulator-metal waveguides. The plasmon-induced absorption (PIA) effect, in which transmission characteristics completely differ from those of a plasmon-induced transparency system, is demonstrated in the DSR system. The performance of the proposed structure is investigated using the finite-difference time-domain method. A transmission dip occurs at the former peak wavelength of the DSR, whereas two transmission peaks appear around the window. The influences of coupling distance and stub length on PIA peaks are investigated and analyzed in detail. Abnormal dispersions can be achieved with the windows based on the analysis of phase responses. Such dispersions can be used for fast light applications in a plasmonic waveguide. Furthermore, sensitivities of 560 nm/refractive index unit (RIU) and 615 nm/RIU, with a sensing medium filling in the double-stub cavity, can be achieved for the two PIA peaks. Result approximates twice as much as the sensing medium filling in one stub of the double-stub cavity. In addition, PIA also manifests in the triple-stub resonator. The results indicate the potential applications of DSR in filtering and sensing.