  We investigate the optical response of a system consisting of periodic silver
V-grooves interacting with quantum emitters. Two surface plasmon-polariton
resonances are identified in the reflection spectrum of bare silver grooves,
with the intensity of one resonance being localized near the bottom of the
groove and that of the other resonance being distributed throughout the entire
groove. The linear response of the hybrid silver-emitter system is thoroughly
analyzed by considering the coupling between surface plasmon polaritons and
emitters as the geometry of the grooves and the spatial distribution of
emitters within the grooves are varied. The nonlinear response of the system is
also considered by pumping the emitters with a short, high-intensity pulse. By
changing the duration or the intensity of the pump, the population of emitters
in the ground state at the end of the pump is varied, and it is found (upon
probing with a short pulse) that an increase in the fraction of emitters in the
ground state corresponds to an increase in Rabi splitting. Spatial variations
in the ground state population throughout the emitter region are shown to be a
result of field retardation.
