CAREER: Kirigami-Actuated Adaptive Metasurfaces with Dynamic Tunability enabled by 2D Materials

使用纳米级天线阵列（也称为元表面）开发积极小型化和高度可调的光学器件，在生物医学成像、无人机传感和成像、可穿戴增强现实眼镜和人工智能方面具有广泛的应用。尽管它们有很大的前景，但超表面基本上是静态的，并且由它们的初始几何设计预定义，并且不能在设备操作期间动态地改变。这可能是其光学功能的显著限制。另一方面，自然界的光学解决方案不是静态的，而是可移动的、自适应的和高度可调的。例如，可调虹膜使脊椎动物如鱼类、爬行动物和哺乳动物能够适应8 - 9个数量级的高度可变的光环境。该计划的研究活动旨在通过将机械可移动和光学可调能力引入其设计和制造中，开发具有非常规功能的新一代超轻光学器件。该项目将构建kirigami启发的纳米级致动器，并将其与基于新兴纳米材料的可调超颖表面进行异质集成。这个跨学科项目在物理学，纳米力学，纳米光子学和材料的交叉点提供了独特的机会，这将促进学生接触科学和工程的前沿。该计划还将积极提高在科学和工程的代表性不足的学生的参与。超表面是采用亚波长范围的相控阵天线，其使用亚波长金属和/或介电相移光学元件将光学波前塑造成具有完整0 - 2 π相位轮廓的任意形状。它们的极端紧凑性和重量轻，在为各种成像和传感应用构建显着小型化的光学元件方面具有很大的前景。尽管它们具有潜力，但超颖表面基本上是静态的并且具有有限的可调谐性，限制了它们可以实现的光学功能。该项目的目标是利用新兴的kirigami超材料和货车德瓦尔斯二维材料，使用整体的协同设计方法开发具有前所未有的机械和光学可调性的超表面。本研究计划包括以下几个方面：（1）从弹性应变极限和机械不稳定性两个方面探索纳米机械结构的设计空间和基本极限，构建传统制造方法和微机电系统难以实现的纳米kirigami致动器;（2）研究石墨烯和层状过渡金属二硫属化物中可调的光-物质相互作用，并开发高度可调的超表面;以及（3）为kirigami可调元表面平台的协同设计和异构集成开发创新方法。该研究计划的范围还提供了独特的推广和教育机会，以培养下一代科学家和工程师解决跨学科问题，并扩大启发和指导的代表性不足的学生在科学和工程。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Developing aggressively miniaturized and highly tunable optical devices using nanoscale antenna arrays, also known as metasurface, has a wide range of applications in biomedical imaging, drone-based sensing and imaging, wearable augmented reality glasses and artificial intelligence. Despite their great prospects, metasurfaces are essentially static and predefined by their initial geometry design and cannot be changed on the fly during the device operation. This can be a significant limitation in their optical functionalities. On the other hand, nature’s optical solutions are not static but movable, adaptive and highly tunable. For example, tunable irises enable vertebrates such as fish, reptiles and mammals to adapt to highly variable light environments with a range of 8-9 orders of magnitude. The research activities in this program aim to develop a new generation of ultralight optical devices with unconventional functionalities by introducing mechanically movable and optically tunable capabilities into their design and fabrication. This project will build kirigami-inspired nanoscale actuators and heterogeneously integrate them with tunable metasurfaces based on emerging nanomaterials. This interdisciplinary project provides unique opportunities at the intersection of physics, nanomechanics, nanophotonics and materials, which will promote students’ exposure to the frontiers of science and engineering. The program will also actively enhance the participation of underrepresented students in science and engineering. Metasurfaces are phased array antennas taken to the subwavelength regime, using sub-wavelength metallic and/or dielectric phase shifting optical elements to mold optical wavefronts into arbitrary shapes with a full 0-2π phase profile. Their extreme compactness and lightweight hold great promise in building dramatically miniaturized optical components for various imaging and sensing applications. Despite their potentials, metasurfaces are essentially static and with limited tunability, restricting their optical functions that can be achieved. The objective of this project is to use a holistic, co-design approach to develop metasurfaces with unprecedented mechanical and optical tunability by leveraging emerging kirigami metamaterials and van der Waals two-dimensional materials. The proposed research program includes the following activities: (1) explore the design space and fundamental limits of nanoscale mechanical structures in terms of elastic strain limit and mechanical instability, and build nanoscale kirigami actuators that would be difficult to achieve by conventional fabrication methods and micro-electromechanical systems; (2) investigate tunable light-matter interactions in graphene and layered transitional metal dichalcogenides and develop highly tunable metasurfaces; and (3) develop innovative approaches for the co-design and heterogeneous integration of kirigami tunable metasurface platform. The scope of this research program also provides unique outreach and educational opportunities to train next generation scientists and engineers to tackle interdisciplinary problems, and to broaden inspiration and mentoring of underrepresented students in science 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.