ENHANCEMENT OF OPTICAL NONLINEARITY THROUGH ANISOTROPIC MICROSTRUCTURES

We investigate the polarization dependence of optical nonlinearity enh ancement 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 respe ct to the axis of anisotropy, For parallel polarization, the results s how that the 3D results are qualitatively similar to the 2D case repor ted recently. For perpendicular polarization, the results are markedly different from the parallel counterpart: In contrast to the absorptio n, the enhancement factor actually increases with the anisotropy. Thus the separation of the absorption and enhancement peaks becomes even m ore pronounced than in the parallel polarization case. These results i ndicate a strong polarization dependence of the nonlinear optical resp onsive. (C) 1998 Elsevier Science B.V.