Space-charge–driven second harmonic generation in nanometric conductors

The properties of harmonic waves, carrying a longitudinal electric field and a space-charge density, made up of conduction electrons, are investigated in metals and semi-conductors with the help of a classical analysis. The associated dispersion curve is worked out. These findings are further applied to unravel a novel second harmonic generation mechanism for an electromagnetic wave shone on a nanometric wire, with frequency ranging from the IF up to UV domain. The calculated efficiency in semi-conductors might be higher by 12 orders of magnitude than in metals. Observable predictions are made.