Materials World Network: Understanding the Optical Response of Designer Epsilon-Near-Zero Materials

光学超材料领域——具有定制光学特性的纳米结构复合材料——在过去十年中经历了爆炸式的增长，部分原因是由于制造、表征、计算科学和理论的快速发展。多年来，各种各样的超材料被开发出来，实现了一些突破性的应用，比如超级透镜、电磁斗篷、理想的光学耦合器和光学黑洞。此外，它们有望彻底改变光束导向、远场和近场之间的光耦合以及许多其他光子学相关领域。在超材料中实现的光控制的许多独特方面源于实现极小介电常数的可能性，这种材料通常被称为epsilon-near-zero （ENZ）超材料。事实上，这些材料形成了光学斗篷的内层，使光能够通过亚波长缝隙进行有效的传输，并被认为是元电子电路的基础。因此，ENZ材料的创造，更重要的是，了解它们与复杂光学结构中的光的相互作用，对于未来下一代光子材料的多学科研究变得越来越重要。从材料的角度来看，ENZ响应可以在均匀系统的等离子体频率附近实现，其光学响应由自由电子主导，或者通过将具有正或负介电常数的不同组分组合在一个单一的复合“元”材料中。在此，我们建议对复杂ENZ材料体系中的光-物质相互作用进行全面的研究。国际团队的联合专业知识将为实验研究基于均质和复合材料的复杂ENZ-含系统的电磁特性提供一个独特的机会，ENZ频率跨越可见光到中红外频率范围，并由共同的理论框架统一。我们联合的独特实验能力将使我们能够描绘与真正的ENZ材料相关的普遍物理学，并评估这些高需求介质的实际效益。

The area of optical metamaterials - nanostructured composites with tailored optical properties - has experienced explosive growth over the past decade, fueled in part by rapid developments in fabrication, characterization, computational science and theory. Over the years, various metamaterials have been developed to enable several groundbreaking applications, such as superlens, electromagnetic cloaks, ideal optical couplers and optical black holes. In addition, they hold the promise to revolutionize beam steering, coupling of light between far- and near-field and many other photonics-related areas. Many of the unique aspects of light control realized in metamaterials originate from the possibility of achieving vanishingly small permittivity, materials which are often referred to as epsilon-near-zero (ENZ) metamaterials. Indeed, these materials form the inner layer of optical cloaks, enable efficient light transfer through subwavelength slits, and have been suggested as the foundation for metatronic circuitry. Therefore, the creation of ENZ materials and, more importantly, the understanding of their interaction with light inside complex optical structures, have become increasingly important for future multidisciplinary research for next-generation photonic materials. From the materials standpoint, ENZ response can be achieved either in vicinity of the plasma frequency in homogeneous systems whose optical response is dominated by free electrons or by combining distinct components with either positive or negative permittivity together in a single composite "meta-"material. Here we propose to perform a comprehensive study of light-matter interaction in complex ENZ material systems. The combined expertise of the international team will provide a unique opportunity to experimentally study the electromagnetic properties of complex ENZ-containing systems based upon both homogenous and composite materials, with ENZ frequencies spanning the visible to mid-IR frequency ranges and unified by common theoretical framework. Our joint unique experimental capabilities will allow us to delineate the universal physics associated with real ENZ materials and assess the practical benefits of these highly demanded media.