Pockels is a term used to describe an electro-optic phenomenon that occurs in certain materials. Synonyms for pockels include electro-optic effect, Pockels effect, and Kerr effect. These terms all describe the same phenomenon when an electric field changes the refractive index of a material, affecting the propagation of light through it. Other related terms include birefringence and polarization rotation, which are both caused by the interaction of light with electric fields in materials. Understanding these phenomena is important in fields such as optics and telecommunications, where the manipulation of light through electric fields is crucial.