The
Kerr effect, also called the
quadratic electro-optic effect (QEO effect), is a change in the
refractive index of a material in response to an applied
electric field. The Kerr effect is distinct from the
Pockels effect in that the induced index change is
directly proportional to the
square of the electric field instead of varying linearly with it. All materials show a Kerr effect, but certain liquids display it more strongly than others. The Kerr effect was discovered in 1875 by
John Kerr, a Scottish physicist.