Novel Aspects of Topological Photonics in Open Optical Systems: Non-Hermiticity and Fano-Resonances

非技术描述：我们控制光散射和传播的能力是现代技术的核心，从智能手机相机的镜头到数据中心的光纤网络。当今光学部件的许多功能改进是通过使用新的或改进的材料来实现的。超材料的概念进一步使这一方法成为可能，因为它提供了具有任何自然材料系统所不具备的特性的人工结构材料。在被称为拓扑超材料的特殊设计结构中，可以发现一种被称为坚固性的独特的工程特性。拓扑超材料允许引导光，对任何材料或设备中不可避免地存在的障碍和缺陷前所未有的不敏感，从而颠覆了关于光传播和散射的常见概念。最重要的是，拓扑超材料为光学材料和器件提供了一个新的平台，它们对制造误差的容忍度要高得多。在这个项目中，我们的目标是设计和测试这样的光学器件，其功能可以容忍制造缺陷和环境因素。该项目是跨学科的，连接了基础科学和应用科学的各个领域。计划对高中和本科少数民族学生进行大量外展工作。为当地学校的高中生举办的活动包括通过CCNY暑期科学计划在PI的实验室进行的暑期研究。技术描述：拓扑光子学为光学散射提供了一个全新的视野，可以被利用来以局部非均匀的方式操纵光的相位和幅度。这表明，其拓扑模式泄漏到周围介质中的开放式拓扑超材料，例如在纳米尺度上图案化的二维超表面，可能提供新的机制来控制光的散射，从而使新的方法能够产生理想的散射图案。另一方面，系统的开放性使光子系统成为非厄米特系统，这本身可能会以一种不平凡的方式影响超材料的拓扑性质。这个项目的目标是了解拓扑和非赫米性之间相互作用的各个方面，并探索开放系统中拓扑健壮性的极限。我们的研究揭示了拓扑模泄漏到自由空间的作用，以及它们与入射光的相互作用。对这些性质的理解使得一类新的具有拓扑保护的拓扑光学器件成为可能。在这个项目中，我们的目标是设计和测试拓扑栅格、超表面、平板透镜和涡流相位板。拟议的研究计划跨越了基础科学和应用科学、光学、光子学和凝聚态物理等领域。该项目为从高中到研究生阶段的学生提供了参与所有阶段研究的机会，并获得了在光子材料和器件方面的实践经验。通过向学生开放拓扑超材料研究的机会，该项目进一步吸引了新兴一代在物理和工程领域追求职业生涯。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical description: Our ability to control light scattering and propagation is at the core of modern technologies, from lenses in smartphone cameras to optical fiber networks in datacenters. Many advancements in functionality of today's optical components are attained by using new or improved materials. The concept of metamaterials further enables this approach by offering artificially structured materials with properties absent in any natural materials system. One such unique engineered property, known as robustness, is found in specially designed structures referred to as topological metamaterials. Topological metamaterials allow guiding light with unprecedented insensitivity to obstacles and defects, inevitably present in any material or device, thus upending common notions of propagation and scattering of light. Most importantly, topological metamaterials offer a new platform for optical materials and devices exhibiting significantly higher tolerance to fabrication errors. In this project, we aim to design and test such optical devices, whose functionality is tolerant to both fabrication imperfections and environmental factors. This project is interdisciplinary in nature, bridging areas of fundamental and applied sciences. Significant outreach efforts towards high school and undergraduate minority students are planned. Activities for high school students from local schools include summer research conducted in the PI's laboratory through CCNY Summer Science Program.Technical description: Topological photonics offers a fundamentally new vision on optical scattering, which may be exploited to manipulate the phase and amplitude of light in locally non-uniform ways. This suggests that open topological metamaterials with their topological modes leaking into a surrounding medium, such as two-dimensional metasurfaces patterned on the nanoscale, may offer new mechanisms of controlling scattering of light and thus enabling new approaches to generate desirable scattering patterns. On the other hand, the open character of the system, which renders photonic systems non-Hermitian, may itself affect topological properties of metamaterials in a nontrivial way. The goal of this project is to understand aspects of the interplay between topology and non-Hermiticity, and to explore the limits of topological robustness in open systems. Our research reveals the role of leakage of topological modes into free-space, and of their interaction with incident light. Understanding these properties enables a new class of topological optical devices endowed with topological protection. Within this project we aim to design and test topological gratings, metasurfaces, flat-lenses, and vortex phase plates. The proposed research plan bridges areas of fundamental and applied science, optics, photonics, and condensed matter physics. The project presents opportunities for students from high-school to the graduate level to get involved in all stages of research, and to obtain hands-on experience in photonic materials and devices. By opening opportunities in research on topological metamaterials to students, this project further attracts emerging generations to pursue careers in physics and engineering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.