Yao Jin, Fan Yubin, Gao Yunhui, Lin Rong, Wang Zhihui, Chen Mu Ku, Xiao Shumin, Tsai Din Ping
Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Light Sci Appl. 2025 Jan 30;14(1):65. doi: 10.1038/s41377-024-01728-3.
Combining bright-field and edge-enhanced imaging affords an effective avenue for extracting complex morphological information from objects, which is particularly beneficial for biological imaging. Multiplexing meta-lenses present promising candidates for achieving this functionality. However, current multiplexing meta-lenses lack spectral modulation, and crosstalk between different wavelengths hampers the imaging quality, especially for biological samples requiring precise wavelength specificity. Here, we experimentally demonstrate the nonlocal Huygens' meta-lens for high-quality-factor spin-multiplexing imaging. Quasi-bound states in the continuum (q-BICs) are excited to provide a high quality factor of 90 and incident-angle dependence. The generalized Kerker condition, driven by Fano-like interactions between q-BIC and in-plane Mie resonances, breaks the radiation symmetry, resulting in a transmission peak with a geometric phase for polarization-converted light, while unconverted light exhibits a transmission dip without a geometric phase. Enhanced polarization conversion efficiency of 65% is achieved, accompanied by a minimal unconverted value, surpassing the theoretical limit of traditional thin nonlocal metasurfaces. Leveraging these effects, the output polarization-converted state exhibits an efficient wavelength-selective focusing phase profile. The unconverted counterpart serves as an effective spatial frequency filter based on incident-angular dispersion, passing high-frequency edge details. Bright-field imaging and edge detection are thus presented under two output spin states. This work provides a versatile framework for nonlocal metasurfaces, boosting biomedical imaging and sensing applications.
将明场成像和边缘增强成像相结合，为从物体中提取复杂的形态信息提供了一条有效途径，这对生物成像尤为有益。复用超表面为实现这一功能提供了有前景的候选方案。然而，目前的复用超表面缺乏光谱调制，不同波长之间的串扰会影响成像质量，特别是对于需要精确波长特异性的生物样品。在此，我们通过实验展示了用于高品质因子自旋复用成像的非局域惠更斯超透镜。连续谱中的准束缚态（q-BICs）被激发以提供90的高品质因子和入射角依赖性。由q-BIC与面内米氏共振之间类似法诺的相互作用驱动的广义克尔条件打破了辐射对称性，导致偏振转换光产生具有几何相位的透射峰，而未转换光则呈现没有几何相位的透射谷。实现了65%的增强偏振转换效率，同时未转换值最小，超过了传统薄非局域超表面的理论极限。利用这些效应，输出偏振转换态呈现出有效的波长选择性聚焦相位分布。未转换的对应物基于入射角色散充当有效的空间频率滤波器，通过高频边缘细节。因此，在两种输出自旋状态下实现了明场成像和边缘检测。这项工作为非局域超表面提供了一个通用框架，推动了生物医学成像和传感应用的发展。
