UC Irvine

Field emission takes place upon focusing propagating surface plasmon polaritons (SPP) at the apex of a sharp metal tip. The effect is demonstrated with remotely launched SPPs on silver and gold probe tips. We couple femtosecond laser pulses through a grating inscribed on the taper of a smooth, silver wire 30um from the apex. Field-emitted current is directly correlated with the radiation of the super-focused SPP at the apex. Both current and radiation at the apex are measured as a function of incident polarization on the grating. In the absence of incident light at the apex, the local field of the "naked" surface plasmon modulates the tunneling barrier that drives the field emission. We give a detailed analysis of the governing dynamics in the presence and absence of an applied extractor field, and aim to distinguish between mechanisms governing measured current. Independent of the distribution of the electrons in the metal half-space the emission acquires coherence by the time-dependent field of the plasmon in the vacuum half-space.