Collaborative Research: Nonlinear Optics of Photonic Topological Insulators

摘要的非技术部分：基于控制和操纵光的技术以无数种方式影响着我们的生活：从实现超高速互联网速度的光纤，汽车的激光制造，到提供清洁能源的太阳能电池-光学设备无处不在。通常，给定器件的性能受到制造缺陷的限制：随机缺陷会导致不必要的光散射，从而阻碍其流动并增加不必要的噪声。研究者Rechtsman和Chen将展示一种完全抑制这种散射的方法：所谓的光束的“光子拓扑保护”。这一概念借鉴于固态物理学（其目标是保护电流不受散射），已经被证明是有效的，并提供了赋予各种各样的设备前所未有的健壮性的可能性。为了在实验室中测试这些概念，研究人员将制造波导阵列（一系列用于光的“线”，它们一起形成所需的器件），嵌入一种对所谓的“非线性”光学器件特别有用的玻璃中。通过合理设计波导阵列，可以在多种不同的器件中实现对散射的抑制。这对光学设备的影响是显而易见的：提高设备效率或降低制造成本（或两者兼而有之）。此外，作者希望他们的工作能够“阐明”在许多情况下防止散射的拓扑保护的一般波现象，包括声波，微波，光波，甚至电子波。摘要技术部分：“拓扑绝缘体”领域已经吸引了凝聚态物理十年，由于这些材料的普遍性质，并在自旋电子学和量子计算惊人的应用。最近的研究表明，它们的关键特性——防止无序散射的“拓扑保护”——可以用具有工程线性色散特性的波导阵列中的光子来实现，以保持边缘模式。本提案将探讨光子拓扑绝缘体（PTIs）的非线性光学性质。通过在非线性光学基片（如硫系玻璃）上制作高质量的PTI波导阵列，本研究项目将探索边缘模式的非线性特性及其潜在应用。由于pti具有根本不同的色散，因此对这些结构中的非线性光学的新理解必然会产生新的科学知识和设备应用，这将对高度跨学科的知识团体产生极大的兴趣。本项目的活动包括：(1)对光子拓扑系统中的非线性效应（即调制不稳定性和孤子）进行分析和数值模拟的理论工作；(2)在具有高非线性响应的硫系玻璃中制造（激光写入光子晶体型结构）；(3)通过注入峰值功率近红外光和观察空间衍射图来表征结构。PI和co-PI之间的合作以及互补的专业知识将使拟议项目从理论研究到器件制造再到表征取得成功。如果成功，光子拓扑保护可以潜在地用于显著提高光学器件的性能，如多路复用系统、全光开关和光束整形系统，以及任何受制造混乱限制的光学应用。

Collaborative Research: Endowing nonlinear optical devices with unprecedented robustness: overcoming fabrication disorder by "topological protection" against parasitic scatteringNon-technical section of abstract:Technology based on controlling and manipulating light affects our lives in countless ways: from the optical fibers that enable ultrafast internet speeds, laser manufacturing of automobiles, to solar cells that provide clean energy - optical devices are ubiquitous. Very often, the performance of a given device is limited by fabrication imperfections: random defects that cause unwanted scattering of light, which impedes its flow and adds unwanted noise. Investigators Rechtsman and Chen will demonstrate a method to completely suppress such scattering: so-called "photonic topological protection" of light beams. This concept, borrowed from solid-state physics (in which the goal was to protect electronic current from scattering) has already been demonstrated to work, and offers the possibility of endowing a wide class of devices with unprecedented robustness. In order to test these concepts in the lab, the investigators will fabricate waveguide arrays (a series of "wires" for light that together form a desired device) embedded in a type of glass that is particularly useful for so-called "nonlinear" optical devices. With proper design of the waveguide array, suppression of scattering will be demonstrated in multiple different devices. The implications to optical devices are clear: increased device efficiencies or cheaper fabrication costs (or both). Moreover, the authors expect their work to "shed light" on the general wave phenomenon of topological protection against scattering in many contexts, including acoustic waves, microwaves, optical waves, and even electron waves. Technical section of abstract:The field of "topological insulators" has captivated condensed matter physics for ten years, due to these materials' universal properties, and striking applications in spintronics and quantum computing. It was recently demonstrated that their key property -"topological protection" against scattering by disorder- could be achieved with photons in waveguide arrays with engineered linear dispersion properties to preserve edge modes. This proposal will explore the nonlinear optical properties of Photonic Topological Insulators (PTIs). Through the fabrication of high quality PTI waveguide arrays in nonlinear optical substrates such as chalcogenide glass, this research project will explore a nonlinear properties of edge modes and their potential applications. Since PTIs have a fundamentally different dispersion, a novel understanding of nonlinear optics in these structures is bound to yield new scientific knowledge and device applications, which will be of great interest to a highly cross-disciplinary set of intellectual communities.The activities of this project are: (1) theoretical work to analytically and numerically model nonlinear effects (i.e., modulation instability and solitons) in photonic topological systems; (2) fabrication (laser-written photonic crystal-type structures) in chalcogenide glass, which has a high nonlinear response; (3) characterizing the structures by injecting high-peak-power near-infrared light and observing spatial diffraction patterns. The collaboration between PI and co-PI with complementary expertise will enable the success of the proposed project from theoretical studies to device fabrication to characterization. If successful, photonic topological protection can potentially be used to dramatically improve the performance of optical devices such as multiplexing systems, all-optical switches and beam-shaping systems - and indeed any optical application limited by fabrication disorder.