A theoretical model to calculate linear electro-optic effect in crystals

A simplified theoretical model is suggested to deal with the phonon–electronic coupling process and then to calculate electro-optic coefficients in which the interaction between the lattice vibrations induced by low frequency external electric field and electrons can be contributed. Results show that the dominant contribution to the electro-optical effect should be ascribed to the new correction term deduced from interaction between lattice vibrations and electron motion, rather than the pure electron contribution. The differences of the magnitude of the correction for different materials mainly come from the differences of their static dielectric constants.