Nonlinear optical phenomena in nanowires

The theory of second harmonic generation (SHG) in nanowires with different dielectric constants from their environment is developed. A nonuniform distribution of the optical electric field created by image forces results in strong SHG even in materials with inversion symmetry. Integral intensity, spatial distribution, and the polarization of the SHG depend dramatically on the light polarization, as well as on the mutual orientation of the light wave vector and nanowire axis. In semiconducting or dielectric nanowires, the SHG is maximal when the light polarization is parallel to the nanowire axis. In metallic nanowires, the SHG is a function of the light frequency omega being maximal when omega or 2 omega coincide with the surface plasmon frequency. At the first resonant frequency, the SHG is caused mostly by light polarized perpendicularly and at the second frequency-parallel to the nanowire axis. (c) 2007 American Institute of Physics.