Plasmon-induced transparency based on a triangle cavity coupled with an ellipse-ring resonator.

In this paper, a novel compact plasmonic system is introduced to realize the phenomenon of plasmon-induced transparency. The proposed device consists of a triangle defect coupled with an ellipse-ring resonator based on a metal-insulator-metal platform. By the finite-difference time-domain method, the transmission characteristics are numerically studied in detail. In order to verify the simulation results, the coupled mode theory is utilized. In the following, the effect of geometrical parameters, namely, the major and minor radii of the ellipse-ring and the gap between cavities, are investigated. Moreover, the fundamental factors of transmission spectra including intrinsic Drude loss and refractive index of dielectric region are studied. As a result, the transmission peak is obtained near 70% and the full width at half-maximum is close to 28 nm. The sensitivity and figure of merit of the proposed structure are 860 nm/RIU and 31.6  RIU, respectively. The mentioned compact structure has the ability and potential to be used in integrated optical circuits like slow light devices, nanoscale filters and nanosensors.