Second-Order Nonlinear Optical Properties of Metal Nanostructures and Metamaterials
Fu Xiang Wang, Francisco J. Rodriguez, Hannu Husu and Martti Kauranen
We review the state-of-the-art regarding the second-order nonlinear optical response of metal nanostructures and metamaterials. The present nanofabrication of metal nanostructures gives rise to defects and other deviations from the ideal structure. Such factors may break the intended symmetry of the structure and give rise to nonlinear signals, which are ideally forbidden. Although second-order effects are electric-dipole-forbidden in the bulk of centrosymmetric materials, they become allowed through magneticdipole and electric-quadrupole effects. Improved understanding of the role of the surface and bulk effects in the second-order response of metals is needed in order to develop proper theoretical models for nonlinear metal nanostructures.
Keywords: Metal nanostructures, metamaterials, nonlinear optics, plasmons, multipole effects, electric-dipole response, magnetic-dipole response, electric-quadrupole response.