Self-complementary metasurfaces for designing terahertz deflecting circular-polarization beam splitters

Metasurfaces provide a broad range of functionalities related to wavefront manipulation in different frequency ranges with the advantage of subwavelength thickness. In this work, we numerically and experimentally investigate a terahertz splitter of circularly polarized beams based on a spatially nonuniform metasurface composed of self-complementary unit cells. When illuminated with circular polarization, the metasurface creates a deflected cross-polarized beam while transmitting a co-polarized beam in the normal direction. Despite the existence of two reflected beams leading to reflective losses, the metasurface is single-layer and is easy to design and fabricate. A required linear phase gradient for the cross-polarized beam can be obtained by adjusting only one design parameter of unit cells.