  This paper deals with the temporal nonlinear dynamics of plasmon-solitons in
a plasmonic waveguide. Duffing equation is recognized as the temporal part of
the nonlinear amplitude equation governing the plasmonic waveguide. It is shown
that Duffing oscillator waveforms stand for the temporal nonlinear dynamics of
plasmon-soliton waves. The exchange of Lorentz-type bright and dark solitons
energies gives rise to a Fano resonance. It is thus shown that the interaction
of solitons and the formation of plasmon-solitons is inherently nonlinear. It
is accordingly indicated that the nonlinear modulation of the plasmon-solitons
is achievable via tuning the nonlinearity of the plasmonic waveguide.
