Giant third optical harmonic generation in island silver films

Giant third optical harmonic (TH) generation has been experimentally observed in island silver films. The TH intensity in the island silver films studied is more than two orders of magnitude higher than the value observed for the smooth surface of a homogeneous silver film. The mechanism of enhancement of the nonlinear cubic response is associated with the resonance enhancement of the local optical field at the TH wavelength, which is caused by the excitation of local surface plasmons in the ensemble of metal nanoparticles.