CAREER: Epsilon-Near-Zero Conducting Oxide Metasurface Perfect Absorbers, Color Filters, and Beam Steering Devices with Gate-tunability

从镜头到滤光片的传统光学元件在现代成像和显示技术中发挥着至关重要的作用，例如光学相机的图像传感器、智能手机的显示器和精确的光学成像显微镜。然而，缩小光学系统尺寸的压力持续存在。超表面是一种纳米结构的超薄表面，它提供了一种控制透射、反射和散射光的相位和振幅的新方法。由于超表面几乎是平坦的（典型厚度为100纳米），它们可以在广泛的电磁波谱范围内实现新型超薄光学元件，如平面透镜、波片和全息表面。然而，大多数超表面的光学性质是固定在纳米结构上的，这限制了许多实际应用。因此，有必要开发一种超薄超表面的可调版本。该项目的第一个目标是建立可电子调谐的导电氧化物超表面，可用于各种下一代成像和显示技术（例如可调谐的完美吸收器，彩色滤光片，光束转向装置等）。该项目的第二个目标是利用我们的纳米光子研究和基础设施，为两年制技术学院学生、大学本科生和研究生提供未来学术和工业生涯所需的纳米光子技能和知识。此外，该项目与当地学校和当地科学博物馆的活动将提供令人兴奋的机会，以有趣和信息丰富的方式向学生和公众介绍纳米光子概念。技术描述：光学超表面是具有亚波长厚度的单层或多层结构，可以产生光的相位、振幅或偏振的突变。它们显示出非凡的光操作前景，并可能实现新型超薄光学元件，如平面透镜、全息图和光学涡旋产生/探测设备。虽然超表面在未来的基础进步和新型光学应用中具有相当大的前景，但缺乏有效的光学可调性和低光学效率是限制其在广泛光学应用中的关键问题。该项目的长期目标是开发一个综合的研究和教育计划，专注于开发高效的纳米级元表面组件及其在元器件中的应用。本CAREER研究的目标是在Epsilon-Near-Zero （ENZ）体制下建立一种高效和宽带的导电氧化物超表面的吸收率、光相位和光谱响应的电管理。为了实现这一目标，PI将通过原子层沉积确定有效控制导电氧化物材料载流子浓度和ENZ频率的方法，这些方法具有场效应可调的超表面共振和梯度指数ENZ多层。建立有效利用超表面电压调谐ENZ共振来操纵光学响应的技术，将有助于开发可调谐超表面光束导向装置、彩色滤光器和完美吸收器，为革命性的纳米光学成像、显示和通信应用开辟道路。将利用该技术的新设备包括用于下一代可见激光雷达技术的高分辨率光束转向装置，用于光/热光伏应用的完美吸收器/光谱分裂元件，用于CMOS光学成像的可调滤色器/镜头和尖端智能手机显微镜/光谱，以及具有纳米级像素的超快空间光调制器。教育目标是将基于先进纳米光子技术的研究和课堂活动结合起来，培养两年制技术学院学生、大学本科生和研究生，使他们具备未来学术和工业生涯所需的纳米光子技能和知识。

Conventional optical components from lenses to filters are playing a critical role in modern imaging and display technologies, such as an optical camera's image sensor, the smartphone's display, and precise optical-imaging microscopy. However, there is an ongoing pressure to shrink the size of optical systems. Metasurfaces, which are ultrathin surfaces patterned with nanostructures, provide a new method to control the phase and amplitude of transmitted, reflected, and scattered light. Because of the virtually flat nature of metasurfaces (typical thickness 100 nm), they can enable novel ultrathin optical components such as flat lenses, waveplates, and holography surfaces over a broad range of the electromagnetic spectrum. However, the optical properties for most metasurfaces are fixed upon their nanofabrication, restricting many real-world applications. Therefore, there is a need to develop a tunable version of an ultrathin metasurface. The first goal of this project is to establish electronically-tunable conducting oxide metasurfaces that could be used for a variety of next-generation imaging and display technologies (e.g. tunable perfect absorber, color filter, beam steering device, etc.). The second goal of this project is to utilize our nanophotonic research and infrastructure to provide two-year technical college students, university undergraduate students, and graduate students with the nanophotonic skills and knowledge necessary for future academic and industrial careers. Furthermore, the project's events with area schools and a local science museum will provide exciting opportunities to introduce nanophotonic concepts to students and the general public in a fun and informative way. Technical description: Optical metasurfaces are single- or few-layer structures with subwavelength thickness which produce abrupt changes in the phase, amplitude, or polarization of light. They show promise for extraordinary light manipulation and could enable novel ultrathin optical elements such as flat lenses, holograms, and optical vortex generation/detection devices. While metasurfaces hold considerable promise for future fundamental advances and novel optical applications, the lack of efficient optical tunability and low optical efficiency are key limiting issues for their use in a wide range of optical applications. The long range goal of this project is to develop an integrated program of research and education focused on developing efficient nanoscale metasurface components and their applications in meta-devices. The objective of this CAREER research is to establish an efficient and broadband electrical management of the absorptivity, optical phase, and spectral response of conducting oxide metasurfaces under an Epsilon-Near-Zero (ENZ) regime. To achieve this objective, the PI will identify approaches which yield efficient control of the carrier concentration of conducting oxide materials and the ENZ frequency with field-effect tunable metasurface resonance and gradient-index ENZ multilayer via atomic layer deposition. Establishing techniques to efficiently exploit the voltage-tuned ENZ resonance in metasurfaces to manipulate optical responses will enable development of tunable metasurface beam steering devices, color filters, and perfect absorbers, opening the path to revolutionary nano-optical imaging, display, and communication applications. Examples of novel devices that would utilize the technology include high-resolution beam steering devices for next generation visible LIDAR technology, perfect absorbers/spectrum splitting elements for photo/thermal-voltaic applications, tunable color filters/lenses for CMOS optical imaging and cutting-edge smartphone microscopies/spectroscopies, and ultrafast spatial light modulators with nanoscale pixels. The educational objective is to integrate research and classroom activities based on advanced nanophotonic technology for training two-year technical college students, university undergraduate students, and graduate students with the nanophotonic skills and knowledge necessary for future academic and industrial careers.