We present the electro optic properties of rhodium-doped barium calcium titanate (BCT) crystals of the congruent melting composition Ba_0.77Ca_0.23TiO₃, in carrying out two types of measurements: electro optic (EO) and absorption. The studied coefficients are r₁₃ and r₃₃ as ordinary and extraordinary waves are involved respectively, the polarized absorption spectra of rhodium-doped barium-calcium-titanate (Rh: BCT) are recorded from 400nm to 1100nm.
We propose an experimental investigation of the EO coefficients, for two different wavelengths corresponding to strong and weak absorption, based on an interferometric set-up. A static electric field is applied out the sample under study, leading to the measurement of the r13 and r33 coefficients. While the phase transition is shifted to the low temperature in compared with BaTiO3 the electro optic coefficients save a high values. Because of the phase transition at low temperatures the values of the coefficients are high compared with BaTiO3.