  We investigate the polarization dependence of optical nonlinearity
enhancement for a uniaxial anisotropic composite of metal nanocrystals in a
dielectric host. Three cases are distinguished depending on whether the
polarization is parallel, perpendicular or unpolarized with respect to the axis
of anisotropy. For the parallel polarization, the results show that the 3D
results are qualitatively similar to the 2D case reported recently. For the
perpendicular polarization, the results are markedly different from the
parallel counterpart: In contrast to the absorption, the enhancement factor
actually increases with the anisotropy. Thus the separation of the absorption
and enhancement peaks becomes even more pronounced than the parallel
polarization case. These results indicate a strong polarization dependence of
the nonlinear optical response.
