Extreme-sensitivity terahertz polarizer inspired by an anisotropic cut-through metamaterial.

Submilliradian accuracy utilizing terahertz waves is used to often discover and observe novel physical phenomena. However, conventional terahertz polarizers cannot simultaneously realize a high extinction ratio, which restricts the sensitivity of the polarization angle, and a high transmission power across a broad frequency band due to the wires involved. Here, inspired by metamaterials, we demonstrate an anisotropic cut-through metal-slit array for an ideal terahertz polarizer with a high extinction ratio and transmission power. Measurements confirm extinction ratios below approximately -50  dB and average transverse magnetic-mode transmission powers of over 80% from 0.3 to 2.2 THz. The extremely sensitive mechanism can shed light on a variety of path-breaking applications such as single-photon detection and quantum information and communication at lower frequencies.