A simple analytic approach to the problem of excitation of surface plasmon polaritons with a dipole nanoantenna

Surface plasmon polaritons can be efficiently excited using attenuated total internal reflection techniques or with diffraction gratings. An alternative way actively studied in recent years is the use of nanoantennas. Here, we show that the amplitude of surface plasmon polariton excited by a nanoantenna can be found analytically using a well-known method for calculation of guided-mode amplitudes in the presence of current sources, which is widely used in the waveguide theory. The calculations are carried out for the simplest 2D case of an infinitely long cylindrical rod of a small radius illuminated by a plane wave and placed in the vicinity of metal substrate parallel to its interface. The validity of the analytical solution is confirmed by the results of numerical simulations.