  The well-known Kerr effect in isotropic fluids consists in the appearance of
uniaxial orientational order and birefringence that grows as the square of the
applied electric field. We predict and observe that at a high electric field,
the Kerr effect displays new features caused by nonlinear dependence of
dielectric permittivity on the field-induced orientational order parameter.
Namely, the field-induced birefringence grows faster than the square of the
electric field; the dynamics of birefringence growth slows down as the field
increases. As a function of temperature, the field induced birefringence is
inversely proportional to the departure from an asymptotic critical
temperature, but this temperature is no longer a constant (corresponding to the
lower limit of the supercooled isotropic phase) and increases proportionally to
the square of the electric field.
