BaTiO₃ crystal films, possessing advanced electrooptic (EO) properties, have spurred a broad interest in research and development of EO modulators for fiber-optic communications. However, the EO coefficient is still at uncontrollable and unoriented states despite it playing a crucial role in developing applicable industrial devices. In this work, accurate measurements of the EO coefficient and birefringence of BaTiO₃ crystal films are implemented with a theorem-based theoretical model, an embedded waveguide/electrode device configuration and a complementary modulation of both the linear and ellipse polarizations. Then, with two state-of-the-art device samples on different crystal films, the final average values of the and are 410 8 pm V⁻¹ and −0.0208 0.0003 for Sample-1 and 624 31 pm V⁻¹ and −0.0138 0.0015 for Sample-2, respectively. Furthermore, a theoretical model for analyzing the measurement accuracies of and is proposed and the accuracy dependences on the two key variables, drive voltage and optic–electric interaction efficiency, are investigated. Finally, the limitations to the measurement accuracy of this methodology are discussed, including the effect of temperature on the measurement accuracy of

具有先进的电光（EO）特性的BaTiO ₃晶体膜引起了人们对用于光纤通信的EO调制器的研究和开发的广泛兴趣。但是，尽管EO系数在开发适用的工业设备中起着至关重要的作用，但它仍然处于无法控制和未定向的状态。在这项工作中，使用基于定理的理论模型，嵌入式波导/电极器件配置以及线性和椭圆偏振的互补调制，可以实现对BaTiO ₃晶体膜的EO系数和双折射的准确测量。然后，在不同的晶体膜上使用两个最先进的器件样本，的最终平均值和对于样本1分别为410 8 pm V ^-1和-0.0208 0.0003，对于样本2分别为624 31 pm V ^-1和-0.0138 0.0015。另外，用于分析的测量精度的理论模型和被提出并在两个关键变量，驱动电压和光电互作用效率的准确度依赖关系，进行了研究。最后，讨论了该方法的测量精度的局限性，包括温度对传感器测量精度的影响。