Plasmonic metasurface for optical rotation

Optical activity, known as optical rotation, has found many applications ranging from optical isolators and concentration determination to sophisticated organic structure analysis. Miniaturization and integration are two continuing trends in the production of photonic devices. However, there are fundamental or technical challenges to further reduce the thickness of the optical elements to generate desirable polarization rotation with broadband and high efficiency. Here in this paper, an efficient method to realize optical rotation for the visible and near infrared light is experimentally demonstrated using an ultrathin metasurface. The polarization rotation originates from the additional phase difference between the two circular polarizations induced by the rectangular metasurface phase grating. Benefiting from the advantages of the reflective metasurface, the fabricated highly efficient device can operate in the broadband. Good agreement between the designed rotation angle and measured results renders this technique very attractive for the practical application in device miniaturization and system integration.