Dichroic polarizing metasurfaces for color control and pseudo-color encoding

In ultracompact image displays based on metasurfaces, the image color is usually controlled by varied nanostructure dimensions, which requires elaborate design and precise manufacturing of nanostructures. Here, we present a metasurface composed of equal-sized nanostructures to control the color of output light, simply by polarization control. Specifically, with resonances occurring in two orthogonal axes for different wavelengths, each nanostructure of the metasurface acts as a biaxial nano-polarizer and reflect most of incident red and green light polarized along the long and short axes, respectively. Hence, by means of reconfiguring the orientations of the biaxial nano-polarizers, the mixture of red and green light with different intensity ratio, governed by Malus law, can be employed to generate a pseudo-colored nanoprinting image. We experimentally demonstrate the proposed metasurfaces by successfully encoding and decoding pseudo-color nanoprinting images right at the metasurfaces. With advantages such as flexible image display and ultra-simple nanostructure design, the proposed dichroic polarizing metasurface can promote advanced research of metasurfaces in color control, ultracompact image display, pseudo-color processing, and many other related fields.