Analysis of a Surface Plasmonic Waveguide of Three Circumscribed Circular Silver Rods

In this paper, a new type of surface plasmonic waveguide (SPW) of three circumscribed circular silver rods is proposed. By employing the finite-difference frequency-domain method, propagation properties like distribution of the magnetic field, propagation length, effective index, mode area, and figure of merit of the fundamental mode are discussed, which all depend on the geometric parameters of the waveguide and the working wavelength. Then the related characteristics are compared with the cases of gain media introduced as the alternate material of the central gap area of the structure and the alternate material of one silver rod. Since the distribution of the transverse magnetic field, effective index, propagation length, mode area, and figure of merit can be adjusted by the geometrical parameters, this kind of SPW might have potential applications in the field of nanoscale circuits and on-chip integration of optical, optoelectronic, and optical devices, as well as sensors.