Propagation of light in an optically active electro-optic crystal of Bi12SiO20: Measurement of the electro-optic coefficient

Abstract

We have studied the phenomenon of light propagation in an optically active linearly birefringent medium with particular reference to the electro-optic crystal of Bi12SiO20. Analytic expressions are given for the ellipticity and the orientation of the emerging light vibration when linearly polarized light is incident normally on the crystal. From these expressions we derive the interesting results that there exists an orientation of the incident light vector for which the output beam is linearly polarized and that the input and output linear vibrations are then symmetrically oriented with respect to the principal birefringent axes of the crystal. This particular angle of orientation is expressed in terms of the linear and circular birefringence of the crystal. Since ellipticity is a function of the electric-field-induced linear birefringence and hence of the electro-optic coefficient of the crystal, we have determined the electro-optic coefficient r41 from a measured value of the ellipticity. The coefficient r41 is found to be (4.1±0.1)×10−12 m/V.