Two-surface plasmon interaction to femtosecond surface spectroscopy

Frequency mixing is demonstrated in degenerate three-wave mixing with two noncollinear beams of femtosecond laser pulses on a metal grating. The observed enhancement of the nonlinear optical response is connected with the synchronized excitation of two surface plasmon-polaritons waves, their nonlinear interaction and photon generation with the sum frequency. The dependencies of this process versus the temporal delay between laser pulses and the mutual spatial overlapping of the beams on the grating surface are studied. Experiments of this type opens a possibility of development of femtosecond time- resolved surface SPP optics and spectroscopy.