The phenomenon of plasmon-induced transparency (PIT) is realized in surface plasmon polariton waveguide at the visible and near-infrared ranges. By adding one and two resonant cavities, the PIT peak(s) was (were) achieved due to destructive interference between the side-coupled rectangle cavity and the bus waveguide. The proposed structures were demonstrated by the finite element method. The simulation results showed that for three rectangle resonators system, not only can we manipulate each single PIT window, but also the double PIT windows simultaneously by adjusting one of the geometrical parameters of the system; for four rectangle resonators system, by changing the widths, the lengths and the refractive index of three cavities simultaneously, we would realize treble PIT peaks and induce an off-to-on PIT optical response. Our novel plasmonic structures and the findings pave the way for new design and engineering of highly integrated optical circuit such as nanoscale optical switching, nanosensor and wavelength-selecting nanostructure.
A novel hybrid plasmonic waveguide of the graphene-coated V-groove and waveguide structure is proposed. The
subwavelength confinements and the propagation of the graphene surface plasmon polaritons modes of the hybrid
graphene-coated waveguide are reached. The mode field energies can be well confined in the V-groove or the waveguide
and be adjusted by varying the chemical potential of graphene. The mode confinement becomes weaker and the
propagation length gets longer as the chemical potential of grapheme increasing. In addition, adjusting the radius of the
waveguide and the frequencies could change the mode propagation and the higher mode is achieved. The finite element
method (FEM) has been employed to study the mode distributions and electromagnetic responses of our designs at midinfrared
We have proposed a couple of plasmonic devices based on graphene sheets and ring resonators. The highly frequency-tunable multi-mode plasmonically induced transparency (PIT) device based on monolayer graphene and rings for the mid-IR region is presented in theory firstly. The multi-mode transparency windows in the spectral responses and slow light effects can be achieved in plasmonic configuration composed of two graphene resonators coupled with single-layer graphene waveguide. By varying the Fermi energy of the graphene, the multi-mode PIT resonance can be dynamic controlled without reoptimizing the geometric parameters of the structures. Based on the coupled mode theory (CMT) and Fabry-Perot (FP), we numerically investigated direct coupling and indirect coupling in the graphene-integrated PIT systems. In addition, the theoretical plasmonic devices based on graphene sheets and ring resonators are also proposed to perform as 1×2 optical spatial switch or ultra -compact Mach-Zehnder interferometer. The finite element method (FEM) is carried on to verify our designs. Those designs may pave the ways for the further development of the compact high-performance plasmonic communication devices.