P. M. Hui, Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, and D. Stroud, Department of Physics, The Ohio State University, Columbus, Ohio 43210-1106

We consider the effective nonlinear susceptibility tensor d(-2\omega; \omega, \omega) for second harmonic generation in a nonlinear composite medium. We derive a simple expression for this susceptibility in terms of the position-dependent tensor d, and three factors which describe the local field enhancement in a corresponding linear medium. The resulting expression can be used to calculate the local-field enhancement of d in many geometries. In the dilute limit, the general expression reduces to a result previously derived.

PACS Nos. 42.70.Nq, 42.65.Pc, 78.66.Sq