coupled to a gold pentamer oligomer by crossing the hot-spot. It is demonstrated that the
hybrid system exhibits a second harmonic (SH) conversion efficiency of∼ 3× 10–5%, which
is among the highest values for a nanoscale object at optical frequencies reported so far.
The SH intensity was found to be∼ 1700 times larger than that from the same nanowire
excited outside the hot-spot. Placing high nonlinear susceptibility materials precisely in …