Theoretical analysis of tunable double plasmon induced transparency in three-ellipse-shaped resonator coupled waveguide

Abstract

The tunable double plasmon-induced transparency (PIT) effects are investigated in the three ellipse-shaped resonators coupled waveguide. By the finite element method, we study the influence of the three ellipse-shaped resonators coupling modes, waveguide structure parameters and the refractive indices of dielectric in three ellipse-shaped resonators on double PIT effects. The waveguide structure consists of three ellipse-shaped resonators, which is analogous to the four-level structure of the atomic system. The bottom ellipse-shaped resonator can be named as a bright mode, the middle and top ellipse-shaped resonators can be seen as dark mode. In order to obtain the ideal double PIT transparency windows, we also numerically analyze the optical transmission characteristics of several three ellipse-shaped resonators coupled waveguide structures. Furthermore, we mainly discuss the transmission spectra in the better three ellipse-shaped resonators coupled waveguide structure as a function of the radii of the long axis in ellipse-shaped resonators, the coupling distance between the bottom ellipse-shaped resonator and the bus waveguide, the coupling distance between ellipse-shaped resonators, and the symmetry broken degree. In addition, we also consider the effect of the refractive indices of dielectric in three ellipse-shaped resonators on double PIT spectra. It is found that the transmission spectra in the three ellipse-shaped resonators coupled waveguide have obvious red shift when the refractive indices of dielectric in three ellipse-shaped resonators increase. All the simulation results may provide the theoretical basis for the potential application of multiple PIT in plasma switches and sensors.

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