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

从透镜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关键作用，如光学相机的图像传感器、智能手机的显示屏和精密光学成像显微镜。然而，缩小光学系统尺寸的压力仍在持续。亚表面是具有纳米结构图案的超薄表面，它提供了一种新的方法来控制透射光、反射光和散射光的相位和幅度。由于准表面具有几乎平坦的性质(典型厚度为100 nm)，它们可以使新型超薄光学元件，如平面透镜、波片和全息表面在广泛的电磁光谱范围内。然而，大多数准表面的光学性质都固定在它们的纳米加工上，这限制了许多现实世界的应用。因此，需要开发一种超薄变形表面的可调版本。该项目的第一个目标是建立电子可调谐的导电氧化物亚表面，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、滤色器、光束控制装置等)。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，为两年制的技术学院学生、大学本科生和研究生提供未来学术和工业职业所需的纳米光子技能和知识。此外，该项目与地区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普通公众介绍纳米光子概念。技术描述：光学亚表面是具有亚波长厚度的单层或几层结构，它会在光的相位、幅度或偏振方面产生突变。它们展示了非凡的光操纵前景，并可能使新型超薄光学元件成为可能，如平板透镜、全息图和光学涡旋产生/检测设备。虽然亚表面在未来的基础发展和新的光学应用方面有很大的希望，但缺乏有效的光学可调谐性和低的光学效率是限制其在广泛的光学应用中使用的关键问题。这个项目的长期目标是开发一个研究和教育的综合计划，专注于开发高效的纳米级亚表面组件及其在亚设备中的应用。这项职业研究的目标是建立一个有效和宽带的电子管理的吸收率，光学相位和光谱响应的导电氧化物准表面在Epsilon-近零(ENZ)制度(Enz)。为了实现这一目标，PI将确定通过原子层沉积的场效应可调亚表面共振和梯度折射率ENZ多层膜来有效控制导电氧化物材料的载流子浓度和ENZ频率的方法。建立有效地利用亚表面中的电压调谐Enz共振来操纵光学响应的技术将使可调亚表面波束控制装置、滤色器和完美的吸收器的开发成为可能，从而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的例子包括用于下一代可见光LIDAR技术的高分辨率光束操纵设备、用于光伏/热伏应用的完美吸收器/光谱分离元件、用于CMOS光学成像和尖端智能手机显微镜/光谱的可调滤色器/透镜，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，为两年制的技术学院学生、大学本科生和研究生培养未来学术和工业职业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.