We show that nonlinear optical rectification (NOR) can be greatly enhanced in the proximity of plasmonic nanostructures. The NOR enhancement in the visible frequency range near Cu-coated SiO${}_2$ nanospheres is calculated by a rigorous first-principle electromagnetic Green's tensor technique. Exemplary compounds with absorption in the visible optical spectrum based on and metalloporphyrin molecules are discussed, exhibiting enhancement factors typically larger than ten. Their spectral properties in relation to NOR are obtained by first-principle electronic structure calculations.

• Received 21 April 2011

DOI:https://doi.org/10.1103/PhysRevB.85.035111