Ultrafast control of grating-assisted light coupling to surface plasmons.

We demonstrate subpicosecond control over the coupling of free-space radiation to surface-plasmon polaritons using 830 and 500 nm period gold gratings. Thermal changes to the electron distribution following irradiation by 100 fs, 810 nm pulses produce a shift of the 570 nm plasmon resonance by approximately 0.75 nm with reflectivity change up to 6% and decay time of approximately 1 ps.