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The optical second harmonic (SH) response from gold metallic nanocylinders with diameters of 80 and 120 nm arranged in hexagonal arrays has been determined as a function of the input fundamental polarization angle for the on- and off-axis transmission geometries and crossed output polarization configurations. For the on-axis transmission geometry, the nonlinear response of the nanocylinders is shown to be mainly incoherent, of pure electric dipole nature and arising from the breaking of the centrosymmetric shape of the body of the cylinders in a plane parallel to the substrate surface. Small angle off-axis experiments however show that the coherent contribution to the nonlinear response is size dependent suggesting that, besides the out-of-plane nonlinearity, retardation effects may also play a nonnegligible role. [ABSTRACT FROM AUTHOR]

The resonance effects on the optical second-harmonic generation from 140-nm silver nanoparticles is studied experimentally by hyper-Rayleigh scattering and numerically by finite element method calculations. We find that the interferences between the broad dipolar and narrow octupolar surface plasmon resonances leads to nonlinear Fano profiles that can be externally controlled by the incident polarization angle. These profiles are responsible for the plasmon-induced suppression of the second harmonic generation. [ABSTRACT FROM AUTHOR]

Abstract: The vertically and horizontally polarized second harmonic responses from arrays of gold metallic nanocylinders with different two-dimensional spatial organization, namely square, hexagonal and random arrangements, have been determined in transmission as a function of the input fundamental polarization angle. The results demonstrate that the second harmonic response is incoherent, resulting from the breaking of the centrosymmetry of the shape of the nanocylinders by surface defects. As a result, no effect from the geometrical arrangement of the nanocylinders on the substrate is observed. [Copyright &y& Elsevier]