论文标题
极化 - 光子耦合在超快Terahertz激发铁电的兴奋中的作用
Role of Polarization-Photon Coupling in Ultrafast Terahertz Excitation of Ferroelectrics
论文作者
论文摘要
我们研究了通过超快Terahertz（THZ）电场脉冲对极化 - 光子耦合（特定于极化振荡诱导的辐射电场）在铁电薄膜激发中的作用。开发分析理论是为了预测如何通过辐射电场和外延菌株调节三维软模式声子（固有极化振荡）的频率和松弛时间。然后使用动态相位场模型模拟了紧张的单域铁电薄膜中谐波偏振振荡的超快THZ脉冲驱动的激发，该模型将对耦合的应变偏振仪动力学进行模拟。从这种数值模拟中提取的频率和放松时间与分析预测非常吻合。在相对较薄的膜中，可以预测辐射电场会稍微降低频率，但会大大缩短松弛时间。这些结果证明了在理解和预测铁电材料对THZ超快脉冲和较高频率的响应时考虑极化 - 光子耦合的必要性。
We investigate the role of polarization-photon coupling (specifically, polarization-oscillation-induced radiation electric field) in the excitation of ferroelectric thin films by an ultrafast terahertz (THz) electric-field pulse. Analytical theory is developed to predict how the frequencies and relaxation time of three-dimensional soft mode phonons (intrinsic polarization oscillation) are modulated by radiation electric field and epitaxial strain. Ultrafast THz-pulse-driven excitation of harmonic polarization oscillation in strained single-domain ferroelectric thin film is then simulated using a dynamical phase-field model that considers the coupled strain-polarization-photon dynamics. The frequencies and relaxational time extracted from such numerical simulations agree well with analytical predictions. In relatively thin films, it is predicted that the radiation electric field slightly reduces the frequencies but significantly shortens the relaxational time. These results demonstrate the necessity of considering polarization-photon coupling in understanding and predicting the response of ferroelectric materials to ultrafast pulses of THz and higher frequencies.
