Generation of vector beams with polarization rotation metasurfaces

We theoretically demonstrate high efficiency broadband vector beams generation with polarization rotation metasurfaces composed of L-shaped silver antenna array, silica spacer, and silver ground plane. 0 degrees to 90 degrees arbitrary optical rotation with high degree of linear polarization (DoLP) over a broadband can be achieved readily by adjusting arm length of the L-shaped antenna. And through turning the L-shaped antennas upside down, the 0 degrees to 90 degrees optical rotation can be turned into 0 degrees to -90 degrees. Reflected phase can be shift by pi after a 90 degrees rotation of the L-shaped or G-shaped antennas, while optical rotation angle remains the same. Then six discrete units are designed to realize 0 degrees to 360 degrees polarization rotation with a step of 60 degrees. With the combination of these units, we proposed metamaterial structures for highly efficient generation of radially polarized and azimuthally polarized vector beams.