Effect of polarization state on electro-optic coupling and its application to polarization rotation. 
The effect of the polarization state on electro-optic coupling is studied by using the wave coupling theory of the linear electro-optic effect.  The numerical results show that the polarization state obviously influences the electro-optic coupling.  The conditions for realizing perfect coupling are emphasized.  As an application of perfect coupling, a novel polarization rotator, which can rotate the polarization of a light beam with an arbitrary angle but keep the output intensity unchanged, is presented.