Malus’ law regulating the intensity of light when passed through a polarizer, forms the solid basis for image steganography based on orthogonal polarizations of light to convey hidden information without adverse perceptions, which underpins important practices in information encryptions, anti‐counterfeitings, and security labels. Unfortunately, the restriction to orthogonal states being taken for granted in the common perceptions fails to advance cryptoinformation to upgraded levels of security. By introducing a vectorial compound metapixel design, arbitrary nonorthogonal polarization multiplexing of independent grayscale images with high fidelity and strong concealment is demonstrated. The Jones matrix treatment of compound metapixels consisting of double atoms with tailored in‐plane orientation sum and difference allows point‐by‐point configuring of both the amplitude and polarization rotations of the output beam in an analytical and linear form. With this, both multiplexing two continuous grayscale images in arbitrary nonorthogonal polarization angles and concealing grayscale image on another in an arbitrary disclosure angle window are experimentally demonstrated in the visible TiO2 metasurface platform. The methods shed new light on multifarious metaoptics by harnessing the new degree of freedom and unlock the full potential of metasurface polarization optics.

A proposal of Fano lasing spaser is demonstrated in a superlattice meta-grating, in which the spatial-temporal lasing dynamics is investigated by a semiclassical model that involves the coupling between full-wave electromagnetic equations and electronic rate equations. The out-of-phase dark mode and in-phase bright mode supported by the meta-grating can be independently tailored by the width of the thin strip and the fat strip in each supercell of the meta-grating. It provides a facile way to alter the dark/bright mode to overlap the emission/absorption window of a given four-energy-level gain medium simultaneously, in which case the system exhibits the optimal lasing characteristic. Our findings may provide a useful guideline to design low-threshold and high-efficient miniaturized lasers.