Metasurface structures for spatial filtering of transverse electric optical waves and linearly polarized beams

Ordinary optical beams, including linearly polarized ones, consist of both transverse electric (TE) and transverse magnetic (TM) plane waves. It has been recently shown that a transmissive nonlocal metasurface can be designed to act as an alignment-insensitive low-pass spatial filter for TM-polarized waves. In this work, we design a metasurface that low-pass-filter TE-polarized waves. Then, combining the two types of metasurfaces, we introduce a single cascaded metasurface as an ultrathin two-dimensional spatial filter. The filter is transparent for plane waves at small incidence angles, < 1^∘, and opaque if the angle is larger. The device, being a simple flat surface structure, provides a significant improvement of the beam quality, overcoming the limitations of conventional, bulky, and alignment-sensitive, spatial filters without sacrificing the performance. We believe that our approach holds strong potential for practical applications in shaping and quality enhancement of optical beams.