  This article proposes a novel three-port circulator with a triangular
graphene-based post for the THz region. This new circulator is formed by three
120 symmetrical metal-based waveguides with a multi-layer triangular
graphene-based post. The anisotropic feature for circulation is provided by
magnetically-biased graphene in the triangular post. The DC magnetic bias is
applied in the z-direction. The magnetized, triangular graphene sheet supports
hybrid TM-TE plasmons. To realize the proposed circulator, the structure has
been simulated in COMSOL software. In our simulation results, isolation of -40
dB with a transmission loss of -3.5 dB is obtained at the central frequency of
5 THz for a specific design. The bandwidth of the simulated circulator is
reported 7.25% with respect to the isolation level of -15 dB. It has been shown
that the scattering parameters of the proposed circulator can be changed by
altering the chemical potential of the graphene and DC magnetic bias, which
makes this circulator a tunable device to be utilized in various plasmonic
systems.
