Zhou You, Guo Shuwei, Overvig Adam Christopher, Alù Andrea
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States.
Nano Lett. 2023 Jul 26;23(14):6768-6775. doi: 10.1021/acs.nanolett.3c00772. Epub 2023 Jun 12.
Optical metasurfaces supporting localized resonances have become a versatile platform for shaping the wavefront of light, but their low quality (-) factor modes inevitably modify the wavefront over extended momentum and frequency space, resulting in limited spectral and angular control. In contrast, periodic nonlocal metasurfaces have been providing great flexibility for both spectral and angular selectivity but with limited spatial control. Here, we introduce multiresonant nonlocal metasurfaces capable of shaping the spatial properties of light using several resonances with widely disparate -factors. In contrast to previous designs, the narrowband resonant transmission punctuates a broadband resonant reflection window enabled by a highly symmetric array, achieving simultaneous spectral filtering and wavefront shaping in the transmission mode. Through rationally designed perturbations, we realize nonlocal flat lenses suitable as compact band-pass imaging devices, ideally suited for microscopy. We further employ modified topology optimization to demonstrate high-quality-factor metagratings for extreme wavefront transformations with large efficiency.
支持局域共振的光学超表面已成为塑造光波前的通用平台,但其低品质因数模式不可避免地会在扩展的动量和频率空间中改变波前,导致光谱和角度控制受限。相比之下,周期性非局域超表面在光谱和角度选择性方面提供了很大的灵活性,但空间控制有限。在此,我们引入了多共振非局域超表面,它能够利用具有广泛不同品质因数的多个共振来塑造光的空间特性。与先前的设计不同,窄带共振透射贯穿由高度对称阵列实现的宽带共振反射窗口,在透射模式下实现了同时的光谱滤波和波前整形。通过合理设计微扰,我们实现了适用于紧凑型带通成像设备的非局域平面透镜,非常适合显微镜应用。我们进一步采用改进的拓扑优化来展示用于高效极端波前变换的高品质因数超光栅。