Graphene-Based Multifunctional Three-Port Far-Infrared Components

Two graphene-based T-shaped multifunctional components for THz and Far-Infrared regions are proposed and analyzed. The first component can serve as a divider, a switch and a dynamically controllable filter. This T-junction presents a circular graphene resonator and three graphene waveguides with surface plasmon-polariton waves connected frontally to the resonator. The resonator can be adjusted to work with dipole, quadrupole or hexapole modes. The graphene elements are deposited on a $Si{O}_2$ (silica) and $Si$ (silicon) two-layer substrate. The dynamical control and switching of the component is provided by the electrostatic field which defines the graphene Fermi energy. Numerical simulations show that the first component in the division regime (which is also the regime ON) has the transmission coefficient -4.3 dB at the central frequency for every of the two output ports and the FWHM is 9.5$\mathrm{\%}$. In the OFF regime, the isolation of the two output ports from the input one is about -30 dB. The second component is a T-junction without resonator which fulfils the function of the divider-switch in more than octave frequency band.