Polarization Detection Using Light's Orbital Angular Momentum

Polarization detection has been used for a wide variety of applications. A twisted light beam with a helical phase structure carries an orbital angular momentum. The rapid development of optical metasurfaces has enabled practical generation and manipulation of twisted light beams at subwavelength resolution. Herein, a facile metasurface approach is experimentally demonstrated to directly detect the polarization state of light based on the superposition of twisted light beams. The major axis and ellipticity of the polarized light are measured by the interference pattern of two twisted light beams with same topological charges and opposite signs, while the handedness is determined by using topological charges with different values. The subwavelength resolution, ultrathin nature, and compactness render this technology very attractive for diverse applications including optical communications, optical tweezers, and quantum sciences.