  We propose a scheme for the coupler-free excitation of surface polaritonic
solitons and breathers in a planar plasmonic waveguide structure comprising of
a transparent layer, a metal layer and a layer of three-level lambda-type
atomic medium. In the proposed system, an enhanced Kerr nonlinearity is
achieved via electromagnetically induced transparency (EIT) in the bottom
atomic medium, which can be controlled through proper modulation of the
frequency detunings and Rabi frequencies of the driving laser fields. This
nonlinearity balances the dispersion in the system, thus providing the
necessary condition for the excitation of polaritonic solitons in the proposed
system. As a result, the system yields laterally self-trapped bright and dark
surface polaritonic solitons which are tightly guided at the interface of the
metal and the EIT medium. Furthermore, we investigate the excitation of surface
polaritonic Akhmediev breathers at the metal-EIT medium interface in the
proposed system. A stable propagation of the surface polaritonic Akhmediev
breathers is achieved with proper choice of parameters in the proposed planar
plasmonic waveguide structure. This experimentally feasible scheme could be
significant in the development of highly compact nano-photonic devices in the
optical regime.
