Shape and Size Resonances in Second Harmonic Generation from Plasmonic   Nano-Cavities
  The nonlinear response of sub wavelength nano-cavities in thin metal films is investigated. We report the resonant dependence of the Second Harmonic Generation by individual triangular and square holes on shape, size and wavelength. For cavities with internal nano-corrugations, giant field enhancements are observed, making them excellent candidates for high sensitivity spectroscopy. 
Adi Salomon, Marcin Zielinski, Radoslaw Kolkowski, Joseph Zyss and   Yehiam Prior
cond-mat.mes-hall