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

使用纳米级天线阵列开发高度可调的小型化光学设备，也被称为超表面，在生物医学成像、基于无人机的传感和成像、可穿戴增强现实眼镜和人工智能中有着广泛的应用。尽管有很大的前景，但变形表面本质上是静态的，由其初始几何设计预先定义，并且不能在设备运行期间动态更改。这可能是它们的光学功能的显著限制。另一方面，大自然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，可调虹膜使鱼类、爬行动物和哺乳动物等脊椎动物能够适应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在设计和制造中引入机械可移动和光学可调能力来开发具有非传统功能的新一代超轻型光学设备。该项目将构建以kirigami为灵感的纳米级致动器，并将它们与基于新兴纳米材料的可调亚表面进行异质集成。这个跨学科的项目在物理学、纳米力学、纳米光子学和材料的交叉领域提供了独特的机会，这将促进学生接触科学和工程的前沿。该计划还将积极加强未被充分代表的学生在科学和工程领域的参与。亚表面是相控阵天线，采用亚波长金属和/或介电相移光学元件，将光学波前塑造成具有完全0-2π相位分布的任意形状。它们极其紧凑和轻巧，在为各种成像和传感应用制造显著微型化的光学元件方面有着巨大的前景。尽管有潜力，但超表面本质上是静态的，可调谐性有限，限制了它们所能实现的光学功能。该项目的目标是利用新兴的Kirigami超材料和van der Waals二维材料，使用一种整体的、共同设计的方法来开发具有前所未有的机械和光学可调整性的超表面。拟议的研究计划包括以下活动：(1)从弹性应变极限和机械不稳定性方面探索纳米级机械结构的设计空间和基本极限，并构建传统制造方法和微型机电系统难以实现的纳米级Kirigami致动器；(2)研究石墨烯和层状过渡金属双卤化物中可调的光-物质相互作用，开发高度可调的亚表面；(3)开发Kirigami可调亚表面平台的协同设计和异质集成的创新方法。这一研究计划的范围还提供了独特的外展和教育机会，以培训下一代科学家和工程师解决跨学科问题，并扩大对科学和工程领域代表性不足的学生的启发和指导。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。

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.