Exploring a novel approach to manipulating plasmon-induced transparency

Plasmon-induced transparency (PIT) effect is an important optical phenomenon in plasmonic structures. In this paper, we design a plasmonic structure to realize the manipulation of PIT simply by varying the angle of the ellipse. It consists of a single hexagonal resonator inserting a rotatable ellipse coupled with the metal-insulator-metal (MIM) waveguide. According to the temporal coupled-mode theory, it is found that the PIT effect results from the destructive interference of two modes. The finite-difference time domain (FDTD) simulations reveal that by rotating the angle of the ellipse the transmission of transparency peak can range from 0.9% to 83% as the full width at half maximum (FWHM) of transparency window varies from 0 nm to 68.6 nm. In addition, the influences of other structural parameters such as the side length of the hexagon, radii of the ellipse, the refractive index of the resonator and so on, are also studied by simulations. Since the PIT effect can be regulated in a single resonator without changing other structural parameters, the proposed plasmonic structure has a great significance on highly nano-integrated optical circuits.