Geometric metasurface for simultaneously detecting polarization state and incident angle

Polarization and incident angle are the two fundamental properties of electromagnetic (EM) waves, which can be used to record, store and process information. Thus, the detection of polarization state as well as incident angle of EM waves plays an important role in photonic applications. However, current techniques in detecting the fundamental properties of EM waves are limited to detect only one physical dimension (e.g., polarization) of EM waves. Here we propose and experimentally demonstrate an approach for simultaneously detecting polarization and incident angle of terahertz (THz) waves based on a geometric metasurface platform. By transforming the rotational symmetry associated with the off-axis incident light to the translational symmetry, the quadratic phase profile is encoded into a geometric metasurface, leading to a single focal point with wide field of view (WFOV) for detecting the polarization and incident angle of THz waves. The incident angle can be revealed just by detecting the translational distance from the center of the focal plane, while the polarization state is achieved through the reconstructed Stokes parameters using the intensity and phase of the single focal point. This unique approach enabling multi-dimensional detection may open a new avenue for designing multifunctional THz devices and integrated systems.