Theory of plasmon-enhanced high-harmonic generation in the vicinity of metal nanostructures in noble gases

摘要

We present a semiclassical model for plasmon-enhanced high-harmonicgeneration (HHG) in the vicinity of metal nanostructures. We show that both theinhomogeneity of the enhanced local fields and electron absorption by the metalsurface play an important role in the HHG process and lead to the generation ofeven harmonics and to a significantly increased cutoff. For the examples ofsilver-coated nanocones and bowtie antennas we predict that the requiredintensity reduces by up to three orders of magnitudes and the HHG cutoffincreases by more than a factor of two. The study of the enhanced high-harmonicgeneration is connected with a finite-element simulation of the electric fieldenhancement due to the excitation of the plasmonic modes.