BaTiO₃晶体薄膜波导在电光调制下的偏振态行为研究

Study of Polarization State Behavior of BaTiO₃ Crystal Thin Film Waveguide under Electro-Optic Modulation

摘要: 钛酸钡作为一种新型集成电光材料，凭借其优异的高电光系数(泡克尔斯效应)与宽带宽特性，已成为高性能片上光调制器的核心材料之一。本文围绕钛酸钡晶体薄膜波导电光调制下的偏振态行为展开理论研究，建立了波导结构与电压–相位变化的关联模型，分析了波导结构对晶体双折射的调制作用；通过MATLAB仿真计算，得到了不同电极间隙下相位变化量随驱动电压的演化规律，以及半波电压与电极长度、电极间隙的依赖关系；进一步探究了特定结构参数(电极长度1 mm、电极间隙8 μm)下，光场偏振态随驱动电压的三维演化轨迹，明确了相位变化与偏振态演化的耦合机制。研究结果揭示了BaTiO₃晶体薄膜波导电光调制下偏振态的调控规律，为设计超紧凑、低功耗的BaTiO₃基偏振调制器提供了理论依据与结构优化思路。

Abstract: As a novel integrated electro-optic material, barium titanate (BaTiO₃) has become one of the core materials for high-performance optical modulators due to its excellent high electro-optic coefficient (Pockels effect) and wide bandwidth characteristics. This paper focuses on the theoretical study of the polarization state behavior of BaTiO₃ crystal thin-film waveguides under electro-optic modulation. A correlation model between the waveguide structure and voltage-phase change is established, and the modulation effect of the waveguide structure on the crystal birefringence is analyzed. Through MATLAB simulation, the evolution law of the phase shift with the driving voltage under different electrode gaps, as well as the dependence of the half-wave voltage on the electrode length and electrode gap, are obtained. Furthermore, the three-dimensional evolution trajectory of the optical field polarization state with the driving voltage under the specific structural parameters (electrode length 1 mm, electrode gap 8 μm) is investigated, and the coupling mechanism between the phase change and the polarization state evolution is clarified. The research results reveal the regulation law of the polarization state in BaTiO₃ crystal thin-film waveguides under electro-optic modulation, providing a theoretical basis and structural optimization ideas for the design of ultra-compact, low-power BaTiO₃-based polarization modulators.