High efficiency broadband -90° to 90° arbitrary optical rotation realized with meta reflectarray.

Abstract

We theoretically demonstrate high efficiency broadband -90° to 90° arbitrary optical rotation realized with meta reflectarray composed of a L-shaped silver antenna array, a silica spacer, and a silver ground plane. Co-polarized and cross-polarized components of reflected wave can be manipulated efficiently by adjusting arm length of the L-shaped antenna, and 0° to 90° arbitrary optical rotation with high degree of linear polarization (DoLP) over a broadband can be achieved readily. The phase of cross-polarized field component can be reversed by turning the L-shaped antennas upside down, and 0° to 90° optical rotation can be turned into 0° to -90° rotation. Reflected phase can be shift by π after a 90° rotation of the L-shaped or Γ-shaped antennas, while optical rotation angle remains the same. Thus, rotation angle θ is changed to 180° + θ after the rotation, and we realized 0° to 360° polarization rotation with a step of 60° with the combination of six discrete structure units. In addition, we proposed metamaterial structures for highly efficient generation of vector beams with these units. The high efficiency broadband arbitrary angle optical rotation will profoundly affect a wide range of applications involving optical polarization.