We present an ultra-compact gate-voltage-controlled terahertz power divider based on graphene plasmonic waveguide,
which consists of five graphene ribbons embedded in the polymethylmethacrylate (PMMA) substrate. We have
theoretically explained their mechanisms as bias voltage change induced carrier density of graphene modification and the
coupling coefficients of graphene plasmon effect after carrier density change, respectively. The surface plasmonic
polariton (SPP) propagation and extinction ratio in the graphene-based device are numerically investigated. The
proposed terahertz power divider has a 3dB working band about 0.1THz and its extinction ratio reaches about 39.86dB at
the frequency of 7THz. It anticipated that our proposed compact device is potentially interesting for the terahertz wave
integrated circuit technology.