  Optical properties of hybrid plasmonic waveguides and of low-Q cavities,
formed by waveguides of finite length are investigated numerically. These
structures are of interest as building-blocks of plasmon lasers. We use a
time-harmonic finite-element package including a propagation-mode solver, a
resonance-mode solver and a scattering solver for studying various properties
of the system. Numerical convergence of all used methods is demonstrated.
