AI 中文总结
该研究针对电介质中非局域性对非线性光-物质相互作用的影响这一未充分探索的问题，提出极性晶体中由光学声子传播与离子键非谐性相互作用产生的新型非线性光学过程，可在中心对称材料中产生二阶响应并实现调控与共振增强，为电介质光-物质相互作用开辟了新领域。
AI 中文摘要
当光被限制在深亚波长体积中时，光学响应会呈现非局域特性，但非局域性如何重塑非线性光-物质相互作用，尤其是在电介质中，仍大多未被探索。本文从理论上揭示了极性晶体中，由光学声子传播与离子键非谐性相互作用产生的一类新型非线性光学过程。研究表明，与传统局域非线性不同，该机制甚至能在中心对称材料中产生二阶响应，且这些响应可通过光限制进行调控，并在光学声子共振附近实现共振增强。我们采用密度泛函微扰理论，量化了典型极性晶体中产生的非局域二阶极化率，研究结果将非局域非线性光学确立为电介质中光-物质相互作用的新领域。
英文摘要
When light is confined to deeply subwavelength volumes, optical responses can become nonlocal. Yet how nonlocality reshapes nonlinear light-matter interactions remains largely unexplored, particularly in dielectrics. Here, we theoretically uncover a new class of nonlinear optical processes arising from the interplay between optical-phonon propagation and ionic-bond anharmonicity in polar crystals. We show that, unlike conventional local nonlinearities, this mechanism enables second-order responses even in centrosymmetric materials. Moreover, these responses can be tuned by the confinement and resonantly enhanced near optical-phonon resonances. Using density functional perturbation theory, we quantify the resulting nonlocal second-order susceptibilities in representative polar crystals. Our results establish nonlocal-nonlinear optics as a new regime of light-matter interaction in dielectrics.
