Snapshot Based Terahertz Polarization Recognition via Metasurfaces

Polarization resolution of terahertz waves has become particularly significant. However, conventional polarization detection techniques usually suffer from system complexity and the need for multiple measurements. Here we demonstrate a snapshot based method for resolving the polarization state of terahertz waves based on circularly polarized multiplexed all-silicon metasurfaces. By designing the geometric and dynamic phases, we control the orthogonal circularly polarized components of the incident beam independently and generate two scalar focused beams with one vector vortex beam separately. The transmitted beam profile at the focal plane can be used to visually discriminate between the linearly, circularly, and elliptically polarized states. Then the Stokes parameters of the incident wave can be calculated based on the relative electric field intensity and the direction of the interfering dark fringes, thus determining the polarization state uniquely. The normalized Poincaré sphere drawn from the simulation results also confirms the validity of the design. The experimental results show that we can analyze the polarization state of the incident beam accurately. This method reduces the difficulty of polarization analysis in the terahertz band, and is expected to be applied to various miniaturized systems that need to obtain terahertz polarization information.