Dielectric metasurfaces have emerged as attractive devices for advanced imaging systems because of their high efficiency, ability of wavefront manipulation, and lightweight. The classical spin-multiplexing metasurfaces can only provide two orthogonal circular polarization channels and require high phase contrast which limits their applications. Here, metasurfaces with arbitrary three independent channels are demonstrated by proposing a nonclassical spin-multiplexing approach exploring the low refractive index meta-atoms. A zoom microscope with on-axis tri-foci and a synchronous achiral-chiral microscope with in-plane tri-foci based on silicon nitride metasurfaces are experimentally demonstrated. Based on the on-axis tri-foci metasurface, singlet zoom imaging with three magnifications and a broadband response (blue to red) based on a single metasurface is first demonstrated. A compact microscope (meta-scope) consisting of two metasurfaces with three magnifications of 9.5, 10, and 29X with diffraction-limited resolutions is further constructed, respectively. Utilizing the in-plane tri-foci metasurface, a singlet microscope with three achiral-chiral channels is demonstrated. It offers a magnification of 53X and a diffraction-limited resolution, enabling simultaneous imaging of an object’s achiral and chiral properties. Our multifunctional metasurfaces and meta-scope approaches could boost the applications in biological imaging and machine vision.

Ref:
Nonclassical spin-multiplexing metasurfaces enabled multifunctional meta-scope
C. Sun, Z. Wang, K. S. Kiang, O. Buchnev, D. Tang, J. Yan, J. Y. Ou*
Small, 2404003 (2024) doi: smll.202404003