Control of grating-coupled ultrafast surface plasmon pulse and its nonlinear emission by shaping femtosecond laser pulse

Spatiotemporal nanofocusing of ultrafast surface plasmon polaritons (SPPs) coupled on a metal Au tapered tip with a curvature radius of a few tens of nanometers is deterministically controlled based on the measured plasmon response function. We control the SPP pulse shape and the second harmonic generation at the apex of the Au tapered tip by shaping the excitation femtosecond laser pulses based on the response function. We also adapted a similar control scheme for coherent anti-Stokes Raman scattering (CARS) and achieved selective CARS excitation of a single Raman mode of carbon nanotubes with only a single excitation laser pulse at the apex of the tip.