Metasurfaces for terahertz polarimetry

Abstract

Polarimetry of electromagnetic waves is important for molecular spectroscopy and high-data rate wireless communications in the terahertz frequency regime. Conventional bulk optical systems used to achieve this functionality have several drawbacks including scarcity of available materials, narrow bandwidth and low efficiency. To overcome these limitations, we employ metasurfaces with spatially changing broadband birefringence to attain the same functionality. We present a metasurface designed with birefringent resonators that are rotated to decompose a normally incident wave into its circularly polarized orthogonal components, namely left-handed circularly polarized (LHCP) and right-handed circularly polarized (RHCP) waves. On that basis, polarimetric information on the incident wave can be retrieved, including circular, elliptical and linear polarization states. This functionality is preserved over a simulated bandwidth of up to 76% which corresponds to the frequency region of 0.65 THz to 1.45 THz.