Metasurface Photodetectors for Computational Imaging

传统的用于摄影和显微镜的图像传感器只能可视化入射光的强度分布，而在图像采集过程中，所有与光的局部传播方向和相位轮廓相关的信息都丢失了。为了解决这一限制，提出的研究将开发一种基于纳米光子学技术的新型图像传感器，在这种传感器中，只有沿着预定的、几何可调的一组方向入射的光才能被检测到。当与计算成像技术相结合时，这种独特的行为可以被利用来实现广泛的高级成像功能。具体的例子包括在一次拍摄中产生三维场景的聚焦图像的能力，对其他不可见的透明相位物体进行成像的能力，以及自动检测物体边缘的能力。这些功能非常适合于许多具有挑战性和技术意义重大的应用，例如透明生物细胞的无标签成像，退化条件下（例如雨，雾和水下）的监视和导航，以及计算机视觉的图像识别。拟议的活动还将通过在光学物理、设备工程和数据科学交叉的相关领域培训研究生和本科生，以及通过相关课程开发工作，促进多学科教育。该装置由涂有特殊设计的等离子体超表面（即不同金属纳米粒子的有序二维阵列）的标准光电探测器组成，可以根据入射光的传播方向选择性地传输或反射入射光。工作计划包括电磁设计、纳米制造和原型设备的测试，并通过基于测量设备特性的计算研究和原理验证成像实验来演示其成像能力。越来越复杂的元表面将被开发出来，具有定制的角响应，以满足特定的应用，并能够提供偏振工程和宽带消色差操作。先进的计算成像技术将被用来演示提出的成像功能，从光场采集到相对比成像和光域空间滤波。这项研究将以一种新颖的方式推进超表面的科学和技术，通过探索它们在有源光电器件中的直接集成。此外，它将突出并利用超表面平面光学的极端设计灵活性和尺寸小型化与计算成像的增强信息处理能力相结合的巨大潜力。由此产生的设备有望通过其在高相关性和及时性领域的许多应用产生重大的技术和社会影响，从生命科学到计算机视觉和自主导航。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Traditional image sensors used in photography and microscopy can only visualize the intensity distribution of the incident light, whereas all information related to the local direction of light propagation and phase profile is lost in the image acquisition process. To address this limitation, the proposed research will develop a new class of image sensors based on nanophotonics technology, where only light incident along a predetermined, geometrically tunable set of directions can be detected. When combined with computational imaging techniques, this distinctive behavior can be exploited to enable a wide range of advanced imaging functionalities. Specific examples include the ability to produce focused images of three-dimensional scenes in a single shot, to image otherwise invisible transparent phase objects, and to automatically detect the edges of an object. These capabilities are ideally suited to a multitude of challenging and technologically significant applications – for example label-free imaging of transparent biological cells, surveillance and navigation under degraded conditions (e.g., rain, fog, and underwater), and image recognition for computer vision. The proposed activities will also promote multidisciplinary education through the training of graduate and undergraduate students in relevant areas at the intersection of optical physics, device engineering, and data science, and through related curriculum development efforts. The proposed devices consist of standard photodetectors coated with specially designed plasmonic metasurfaces (i.e., ordered two-dimensional arrays of different metallic nanoparticles) that can selectively transmit or reflect incident light depending on its direction of propagation. The work plan includes the electromagnetic design, nanofabrication, and testing of prototype devices, and the demonstration of their imaging capabilities through computational studies based on the measured device characteristics and through proof-of-principle imaging experiments. Metasurfaces of increasing complexity will be developed with angular response tailored to meet specific applications and capable of providing polarization-engineered and broadband achromatic operation. Advanced computational imaging techniques will be employed to demonstrate the proposed imaging functionalities, from lightfield acquisition to phase contrast imaging and optical-domain spatial filtering. This research will advance the science and technology of metasurfaces in a novel fashion, by exploring their direct integration within active optoelectronic devices. Furthermore, it will highlight and exploit the great potential of combining the extreme design flexibility and size miniaturization of metasurface flat optics with the enhanced information processing capabilities of computational imaging. The resulting devices are promising for a significant technological and societal impact through their many applications in areas of high relevance and timeliness, ranging from the life sciences to computer vision and autonomous navigation.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.