Observation of coherent multiple scattering of surface plasmon polaritons on Ag and Au surfaces

We report the observation of coherent multiple scattering of surface plasmon polaritons in Ag and Au films through attenuated total reflectance in the Kretschman geometry. The pump-probe measurements reveal exponential tails in the amplitude of the reflected light that extend well beyond the pulse correlation time. The exponential tails reflect the temporal decay of surface plasmon polaritons (SPP). This observation and interpretation of SPP decay through scattering from surface roughness suggest the possibility of SPP localization on metal surfaces. An alternative interpretation of the signals, pulse reshaping due to the constant angle SPP modes, is ruled out.