  In the present paper, the collective near-field effects in a two-graphene
sheets plasmonic waveguide loaded with an array of Ag$_2$Se quantum dots
excited by external radiation are theoretically studied. This research aims to
develop a theoretical approach to realizing controllable excitation and the
propagation of surface plasmon polaritons (SPPs) in planar graphene waveguides.
The proposed model is based on the semiclassical description that implies the
dispersion equation's solution for SPPs excited in two coupled graphene sheets
and the embedded quantum dots' energy spectra analysis. Using the finite
difference time domain method, the different near-field patterns realized in
the waveguides depending on the quantum dots' ordering and an external voltage
applied independently to each graphene sheet with additional gold electrodes
are numerically investigated. The research shows that applying external
voltages allows locally changing the graphene chemical potential, thereby
leading to controllable excitation of SPPs in the space between the electrodes.
Under these conditions, the propagation direction of the excited SPPs is
determined by the geometrical configurations of the gold electrodes providing
the required SPP routing. The investigated system offers new opportunities for
near-field energy transport and concentration, which can be applied to develop
ultra-compact photonic devices.
