  A dielectric nonlinear response in model two-phase composites, prepared from
a displacive ferroelectric material with a dominant dielectric response due to
a single oscillator ferroelectric mode and a dielectric material, is
characterized by the existence of new modes due to geometric resonances below
the percolation threshold in the ferroelectric matrix. The geometric nature of
oscilations depends on composition and geometric properties of the mixture.
Generation of higher frequency modes is studied within our model and discussed
for displacive ferroelectric materials of the $BaTiO_{3}$ type. The Bergman
Representation of the effective dielectric function together with our model for
spectral function recently introduced are used simultaneously with theory of
absorption in finite displacive ferroelectric crystals in quasistatic
approximation to describe the physics of the composite. The boundaries of the
present study are within this quasistatic approximation. New ways how to
optimize material properties for nonlinear optics is outlined.
