Light–matter interactions at a particular point in a material may be dominated by properties of the medium at this point, or they could be affected by the electromagnetic properties of the medium in the surrounding regions. In the former case, the medium is said to be local, while in the latter, it is nonlocal. Recent studies of light–matter interactions in composite optical metamaterials showed that nonlocal effects enable new optical phenomena that are not acounted for by the conventional, local effective medium description. Up until now the majority of studies focused on metamaterials with spatially uniform material parameters. However, optical metamaterials with electromagnetic material parameters gradually changing from positive to negative values, so-called transition materials, have been predicted to induce a strong enhancement of the local electric or magnetic field in the vicinity of the zero refractive index point. This opens new opportunities for sensing and low-intensity nonlinear optical applications. Here, we analyze the field enhancement in realistic transition metamaterials consisting of an array of plasmonic cone-shaped rods embedded in a dielectric matrix and demonstrate that optical nonlocality is required to adequately describe this optical response. This work enables the design and practical applications of this new emerging metamaterial platform.

中文翻译：

---

过渡双曲超材料中的非局部效应

在材料中特定点处的光-物质相互作用可能受该点处介质的特性支配，或者可能受到周围区域中介质电磁特性的影响。在前一种情况下，媒体被称为本地媒体，而在后一种情况下，媒体是非本地媒体。对复合光学超材料中光-物质相互作用的最新研究表明，非局域效应使新的光学现象得以实现，而传统的局域有效介质描述却无法解释这种现象。到目前为止，大多数研究都集中在具有空间上统一的材料参数的超材料上。但是，具有电磁材料参数的光学超材料从正值逐渐变为负值，即所谓的过渡材料，据预测，在零折射率点附近会引起局部电场或磁场的强烈增强。这为传感和低强度非线性光学应用提供了新的机会。在这里，我们分析了现实的过渡超材料中的场增强，该材料由嵌入电介质基体中的等离激元圆锥形杆阵列组成，并证明需要光学非局域性才能充分描述这种光学响应。这项工作使这个新兴的超材料平台的设计和实际应用成为可能。我们分析了现实的过渡超材料中的场增强，该材料由嵌入电介质基体中的等离激元圆锥形杆阵列组成，并证明光学非局限性是充分描述这种光学响应所必需的。这项工作使这个新兴的超材料平台的设计和实际应用成为可能。我们分析了现实的过渡超材料中的场增强，该材料由嵌入电介质基体中的等离激元圆锥形杆阵列组成，并证明光学非局限性是充分描述这种光学响应所必需的。这项工作使这个新兴的超材料平台的设计和实际应用成为可能。