铁电体光学性质的动态相场模型
A Dynamical Phase-Field Model for the Optical Properties of Ferroelectrics
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中文总结 AI 辅助
研究铁电材料光学性质设计难题，开发动态相场模型，通过引入电子极化场耦合铁电序与局部光学响应，用于预测复杂铁电微结构光学性质，应用于BaTiO3薄膜，揭示相关特性，建立光-物质相互作用预测通用方法。
中文摘要 AI 辅助
铁电材料因其自发极化与光学性质之间的强耦合，有望用于可控光子器件。然而，由于铁电畴结构与光学响应紧密相连，现有理论方法难以捕捉，其设计颇具挑战。本文通过引入电子极化场，开发了一种将铁电序与局部光学响应直接耦合的动态相场模型，能预测复杂铁电微结构中空间分辨的温度和波长相关光学性质。将该方法应用于BaTiO3薄膜，研究了不同电场和温度下局部折射率和电光响应的演变。结果表明铁电畴结构强烈改变局部电光响应，在畴壁附近超过4000 pm/V，比体单晶值大几倍。模拟定量再现了硅基BaTiO3薄膜中测量的电光系数，并捕捉了多个铁电相变的温度依赖性行为，揭示了相竞争和共存对电光响应的作用。更广泛地说，这项工作建立了一种预测复杂铁电微结构中光-物质相互作用的通用方法，实现了用于光子学的铁电材料的计算设计。
英文摘要
Ferroelectric materials are promising platforms for controllable photonic devices because of the strong coupling between their spontaneous polarization and optical properties. Yet, these materials remain challenging to design because of the close connection between the ferroelectric domain structure and optical response, which no existing theoretical approach can capture. Here, we develop a dynamical phase-field model that directly couples the ferroelectric order to the local optical response by introducing an electronic polarization field. This approach enables the prediction of the spatially resolved temperature- and wavelength-dependent optical properties in complex ferroelectric microstructures. Applying this method to BaTiO3 thin films, we investigate the evolution of the local refractive index and electro-optic response under varying electric fields and temperatures. We show that the ferroelectric domain structure strongly modifies the local electro-optic response, exceeding 4000 pm/V near domain walls, several times larger than the bulk single crystal value (r_51=1300 pm/V). Our simulations quantitatively reproduce the electro-optic coefficient measured in BaTiO3 on silicon films and capture the temperature-dependent behavior across multiple ferroelectric phase transitions, revealing the role of phase competition and coexistence in determining the electro-optic response. More broadly, this work establishes a general approach for predicting light-matter interactions in complex ferroelectric microstructures, enabling the computational design of ferroelectric materials for photonics.
