Second-harmonic generation from metal-film nanohole arrays

The roles of surface plasmon resonance and localized resonances in second-harmonic generation are investigated in a noncentrosymmetrical metallic film with a periodic subwavelength nanohole array. By using a recently developed microscopic classical theory and a three-dimensional finite-difference time-domain algorithm, numerical results show that the second-harmonic intensity is a function of the polarization and wavelength of incident waves. A peak of the second-harmonic intensity is achieved when the incident wave is along the direction perpendicular to the x-axis of nanoholes, which corresponds to the maximal extraordinary optical transmission. Meanwhile, the second harmonic is found to correlate with the group delay of incident waves. (C) 2010 Optical Society of America