Wavelength and Polarization Multiplexed Nonlocal Metasurface for Quantitative Phase Microscopy.

Imaging transparent samples remains an ongoing challenge in the study of unstained biological cells and material samples. Widely used methods trade off system complexity, cost and bulk, computational efficiency, and information content. Here, a nonlocal metasurface located in the object plane is demonstrated for obtaining single-shot, low-noise differential phase contrast images visualizing phase gradients along orthogonal directions in a sample obtained at wavelengths of 613 and 656 nm. These images are sufficient to calculate the quantitative phase introduced into the transmitted optical field by the sample, with experiments showing the recovered phase generated by a spatial light modulator is in good agreement with specified values. This method was also demonstrated to obtain information-rich differential phase contrast images of unstained HeLa cells with the recovered phase excursion values consistent with the literature. These results demonstrate the potential for metasurfaces as a platform for extracting information from an optical field for use in next-generation compact imaging systems with applications in medical diagnostics, biotechnology, and materials science.