Abstract
Nonlinear composite structures show great promise for use in optical switching, signal processing, etc. I derive an effective nonlinear dielectric permittivity of a composite structure where coated ellipsoidal nonlinear particles are imbedded in a linear host medium. The derived expression for the effective dielectric permittivity tensor follows the Clasius-Mossotti approximation. The conditions for the existence of the optical bistability effect in a coated ellipsoidal particle with a nonlinear core and a metallic shell were obtained.