Optical filter and sensor based on plasmonic-gap-waveguide coupled with T-shaped resonators

A novel type of plasmonic filter consisting of metal-insulator-metal bus waveguides coupled with a T-shaped side-coupled cavities and stub waveguides. By finite-difference time-domain (FDTD) simulations, it is found that the resonant wavelength can be controlled by adjusting the length and height of the resonator. The effect of the asymmetry on the transmission property has also been examined. The result demonstrates that the asymmetrical plasmonic waveguide-resonator system performs a plasmonic analogue of electromagnetically induced transparency (EIT) in atomic systems, as confirmed by numerical experiments. The EIT-like transparency window exhibits a distinct resonance shift with respect to a small fluctuation in the refractive index of the surrounding medium, which can be used to increase the sensitivity of the plasmonic sensors. The proposed plasmonic filter and sensor have compact size that may find significant applications in highly-integrated dense wavelength division demultiplexing systems, nanoscale optical switching, and slow-light devices in highly integrated optical circuits and networks. (C) 2015 Elsevier GmbH. All rights reserved.