Second and third harmonic generations in random composites of spheroidal particles

With the aid of the spectral representation and decoupling approximation, we investigate the effective optical susceptibilities for second harmonic generation (SHG) and third harmonic generation (THG) of nonlinear composites media, in which the nonlinear spheroidal particles are embedded in a linear host medium. We emphasize the effect of the granular shape on SHG and THG susceptibilities in two types of microstructures corresponding to those described by the generalized Maxwell–Garnett Theory (MGT) and Effective Medium Approximation (EMA). Numerical results show that large enhancement of SHG and THG can be achieved by the adjustment of the depolarization factor (or the granular shape). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)