EFRI NewLAW: Non-reciprocal, topologically protected propagation using atomically thin materials for nanoscale devices

EFRI NewLAW：使用原子级薄材料用于纳米级设备的非互易、拓扑保护传播

• 批准号: 1741691
• 负责人: Ajit Srivastava
• 金额: $ 200万
• 依托单位: Emory University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-11-01 至 2022-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1741691&HistoricalAwards=false
• 关键词: EFRI; NewLAW; Non; reciprocal; topologically

Reciprocity in optics can be described by the familiar observation: "If I can see you, you can see me." This phenomenon stems from the fact that laws of nature governing light and its interaction with matter on a microscopic level do not prefer any particular direction of time. In other words, if we were to hypothetically reverse the direction of time, the predictions of the laws of nature would remain unaltered. Of course, at a macroscopic scale, this is not the case as we know from experience that the arrow of time has a fixed direction. It turns out that an external magnetic field can break the symmetry of time even at the microscopic scale by picking a preferred direction of propagation, which can lead to a break down of reciprocity. In current optical devices, magnets are used to cause such a one-way propagation of light, which is crucial for optical communications and the Internet. One goal of this project is to achieve non-reciprocity of light without the use of magnets by using a new class of materials, which are atomically thin. Such materials feature an effective magnetic field due to their unique crystal structure and can be used in lieu of an applied external magnetic field for one-way propagation of light. This project aims to realize miniaturized optical devices and circuit elements based on these novel materials, which will allow for faster optical switches and defect-insensitive propagation on a reduced footprint. Such devices have the potential to transform the optical telecommunication industry. During the course of this project, the research team will provide science education and research experiences in cutting-edge technologies to middle school, undergraduate and graduate students, including those students from Historically Black Colleges and Universities, in an effort to enhance the science and engineering workforce of tomorrow. The goal of this project is to realize on-chip, non-reciprocal nanophotonic devices and circuit elements operating at optical frequencies and topologically protected edge states for photons. Such devices will feature novel functionalities such as reconfigurable one-way propagation and steering of light. Non-reciprocal propagation of energy and information in a time-independent and linear system requires broken time-reversal symmetry, which can be achieved by an external magnetic field. We will achieve non-reciprocal propagation at nanoscale in a magnetic-free way with the possibility of active control by external stimuli. Our approach will employ atomically thin materials such as transition metal dichalcogenides with unique electronic and optical properties to achieve these goals. In these materials, which break inversion symmetry, an effective magnetic field in the momentum-space called the Berry curvature is present. Although no net Berry curvature is present in these materials, electric control offers the possibility of spatially local time-reversal breaking and non-reciprocal propagation. In addition, we will rely on the strong light-matter interactions and non-linearity in these materials to increase non-reciprocity and also to realize topologically protected edge states of light. To this end, optical and plasmonic nano-cavities, which enhance light-matter interactions, will be exploited. This research project will advance our fundamental understanding of effective gauge-fields like Berry curvature in low-dimensional materials and how strong light-matter interactions can be exploited to achieve on-chip, reconfigurable non-reciprocity and topological states of light-matter.

光学中的互易性可以用熟悉的观察来描述：“如果我能看到你，你就能看到我。”这种现象源于这样一个事实：在微观层面上控制光及其与物质相互作用的自然法则并不偏好任何特定的时间方向。换句话说，如果我们假设逆转时间的方向，自然法则的预测将保持不变。当然，从宏观来看，情况并非如此，我们根据经验知道，时间之箭有固定的方向。事实证明，即使在微观尺度上，外部磁场也可以通过选择首选的传播方向来打破时间的对称性，从而导致互易性的破坏。在当前的光学设备中，磁铁用于引起光的单向传播，这对于光通信和互联网至关重要。该项目的一个目标是通过使用一类原子薄的新型材料，在不使用磁铁的情况下实现光的非互易性。这种材料由于其独特的晶体结构而具有有效的磁场，并且可以用来代替所施加的外部磁场来实现光的单向传播。该项目旨在实现基于这些新型材料的小型化光学器件和电路元件，这将允许在更小的占地面积上实现更快的光学开关和缺陷不敏感的传播。此类设备有可能改变光通信行业。在该项目期间，研究团队将为中学生、本科生和研究生，包括来自历史上黑人学院和大学的学生提供前沿技术的科学教育和研究经验，以提高科学和工程水平明天的劳动力。该项目的目标是实现片上、不可逆纳米光子器件和电路元件，这些器件和电路元件在光学频率和受拓扑保护的光子边缘状态下运行。此类设备将具有新颖的功能，例如可重新配置的单向传播和光控制。与时间无关的线性系统中能量和信息的非互易传播需要打破时间反转对称性，这可以通过外部磁场来实现。我们将以无磁方式实现纳米级的非互易传播，并有可能通过外部刺激进行主动控制。我们的方法将采用原子薄材料，例如具有独特电子和光学特性的过渡金属二硫属化物来实现这些目标。在这些打破反演​​对称性的材料中，动量空间中存在称为贝里曲率的有效磁场。尽管这些材料中不存在净贝里曲率，但电控制提供了空间局部时间反转破坏和非互易传播的可能性。此外，我们将依靠这些材料中强的光-物质相互作用和非线性来增加非互易性，并实现光的拓扑保护边缘态。为此，将利用增强光与物质相互作用的光学和等离子体纳米腔。该研究项目将增进我们对有效规范场（如低维材料中的贝里曲率）的基本理解，以及如何利用强光与物质相互作用来实现光物质的片上、可重构非互易性和拓扑状态。

项目成果

Femtosecond valley polarization and topological resonances in transition metal dichalcogenides

过渡金属二硫化物中的飞秒谷极化和拓扑共振

• DOI: 10.1103/physrevb.98.081406
• 发表时间: 2017-11-28
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: S. A. O. Motlagh;Jhih;V. Apalkov;M. Stockman
• 通讯作者: M. Stockman

Spatial Separation of Carrier Spin by the Valley Hall Effect in Monolayer WSe 2 Transistors

单层WSe 2 晶体管中谷霍尔效应引起的载流子自旋的空间分离

• DOI: 10.1021/acs.nanolett.8b03838
• 发表时间: 2019-01
• 期刊: Nano Letters
• 影响因子: 10.8
• 作者: Barré, Elyse;Incorvia, Jean Anne;Kim, Suk Hyun;McClellan, Connor J.;Pop, Eric;Wong, H.;Heinz, Tony F.
• 通讯作者: Heinz, Tony F.

Topological Spaser

拓扑Spaser

• DOI: 10.1103/physrevlett.124.017701
• 发表时间: 2020-01
• 期刊: Physical Review Letters
• 影响因子: 8.6
• 作者: Wu, Jhih;Apalkov, Vadym;Stockman, Mark I.
• 通讯作者: Stockman, Mark I.

Topological nanospaser

拓扑纳米航天器

• DOI: 10.1515/nanoph-2019-0496
• 发表时间: 2019-11-08
• 期刊: Nanophotonics
• 影响因子: 7.5
• 作者: R. Ghimire;Jhih;V. Apalkov;M. Stockman
• 通讯作者: M. Stockman

Fundamentally fastest optical processes at the surface of a topological insulator

拓扑绝缘体表面最快的光学过程

• DOI: 10.1103/physrevb.98.125410
• 发表时间: 2018-07-05
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: S. A. Oliaei Motlagh;Jhih;V. Apalkov;M. Stockman
• 通讯作者: M. Stockman