OBSERVATION OF COHERENT MULTIPLE-SCATTERING OF SURFACE-PLASMON POLARITONS ON AG AND AU SURFACES

We report the observation of coherent multiple scattering of surface p lasmon polaritons in Ag and Au films through attenuated total reflecta nce in the Kretschmann geometry. The pump-probe measurements reveal ex ponential tails in the amplitude of the reflected light that extend we ll beyond the pulse correlation time. The exponential tails reflect th e temporal decay of surface plasmon polaritons (SPP). This observation and interpretation of SPP decay through scattering from surface rough ness 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.