Optical nonlinearity enhancement in compositionally graded films of nonspherical nanoparticles

Effect of nanoparticles´ shape and compositionally graded profile on the optical nonlinearity of compositionally graded films is investigated with the aid of the effective medium approximation in conjunction with spectral presentation. Numerical results show that with the suitable adjustment of the particle shape, the resonant band of nonlinear optical properties becomes broad. In addition, for a power-law composition profile p(x) = ax^m, we find that increasing m results in appreciable enhancement of effective non-linearity independent of the particles´ shape. In consequence, the introduction of nonspherical inclusions in compositionally graded films is helpful to produce large optical nonlinearity and even optical figure of merit.