Non-Hermitian and Topological Plasmonic Devices for Light Manipulation at the Nanoscale

光学和光子学在基础科学和尖端技术中都扮演着重要的角色。例子包括太阳能收集和转换、光纤通信和光学数据存储，仅举几例。迫切需要新的策略来进一步推进纳米级光子器件的设计和实现，其中的损耗和缺陷对器件的性能造成了很大的限制。该项目的目标是通过设计材料性质的空间分布和结构拓扑来研究新的现象和功能，如光波的单向传输、缺陷免疫光子态和低输入功率的纳米级激光。该项目的成功将导致朝着开发能耗低、占地面积小、性能稳健的集成光子器件迈出关键的一步，从而为广泛应用的光学信息处理、保密通信、增强的传感和量子技术带来好处。此外，该项目提供了一个跨学科的平台，以吸引学生，特别是那些来自代表性不足群体的学生，并将他们培养成光子学、材料科学、纳米技术和应用物理领域的下一代科学家和工程师。这项研究涉及纳米等离激元、非厄米光子学和拓扑光学。这三个快速增长的领域之间的相互作用具有深远的影响。一方面，等离子体激子表现出了突破衍射极限、产生局部热点和放大数量级电场的显著能力，并显著增强了光-物质相互作用。然而，几何结构的损耗和缺陷对等离子体纳米结构的光学响应和等离子体器件的性能有很大的影响。非厄米特和拓扑物理的概念有可能解决这些挑战。另一方面，到目前为止，非厄米光学和拓扑光子学大多是在微米级特征尺寸的系统中实现的。研究这两个概念是否以及如何能够在纳米尺度上实现新的特性和应用是非常有兴趣的。由于在设计亚波长等离子体元件的几何形状、共振、耦合、色散和复介电常数方面具有很大的灵活性，因此等离子体在这方面提供了一个很好的试验台。该项目包括三个研究方向，包括(1)通过调制复杂平面上的介电常数来演示非厄米等离子体器件中表面等离子激元的单向激发和反射；(2)研究一维和二维非厄米等离子体结构中的拓扑态，这些结构不受缺陷、缺陷和无序的影响；以及(3)低阈值和拓扑保护的等离子体纳米激光器的数值和实验研究。该项目的研究成果将开辟一条新的途径，以前所未有的方式高效地产生、利用和传输光和能源。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。

Title: Non-Hermitian and Topological Plasmonic Devices for Light Manipulation at the NanoscaleOptics and photonics play a vital role in both fundamental science and cutting-edge technologies. Examples include solar energy harvesting and conversion, fiber optic communications, and optical data storage, to name a few. New strategies are urgently needed to further advance the design and implementation of nanoscale photonic devices, in which the loss and defect impose significant limitations on the performance of the devices. The goal of this project is to investigate the novel phenomena and functions, such as unidirectional transport of light waves, defect-immune photonic states, and nanoscale lasers with low input power, by engineering the spatial distribution of material properties as well as the structural topology. The success of the project will lead to a crucial step towards the development of integrated photonic devices with low energy consumption, small footprint, and robust performance to benefit optical information processing, secure communications, enhanced sensing, and quantum technology for a wide range of applications. In addition, the project provides an interdisciplinary platform to engage students, especially those from underrepresented groups, and foster them to become next-generation scientists and engineers in the fields of photonics, materials science, nanotechnology and applied physics. The proposed research lies at the interface of nano plasmonics, non-Hermitian photonics, and topological optics. The interplays among the three rapidly growing fields have profound implications. On one hand, plasmonics has shown remarkable abilities to beat the diffraction limit, generate local hotspots with electric fields amplified by orders of magnitude, and significantly enhance light-matter interactions. However, it is known that the loss and imperfection in geometries strongly influence the optical responses of plasmonic nanostructures and the performance of plasmonic devices. The notion of non-Hermitian and topological physics can potentially address these challenges. On the other hand, up to date, non-Hermitian optics and topological photonics have been mostly realized in systems with the feature size at the micrometer scale. It is of great interest to investigate if and how the two concepts could enable novel properties and applications at the nanoscale. Plasmonics provides an excellent testbed in this regard, thanks to the large flexibility in engineering the geometry, resonance, coupling, dispersion, and complex dielectric constants of subwavelength plasmonic elements. The proposed project consists of three research thrusts, including (1) demonstration of unidirectional excitation and reflection of surface plasmon polaritons in non-Hermitian plasmonic devices by modulating the permittivity in the complex plane; (2) investigation of topological states in one-dimensional and two-dimensional non-Hermitian plasmonic structures, which are immune to defects, imperfections, and disorder; and (3) numerical and experimental study of low-threshold and topologically protected plasmonic nanolasers. The research findings of the project will open up a new route to efficiently generate, harness and transport light and energy in an unprecedented manner.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.