Terahertz linear polarizers fabricated using magnetorheological fluid

Abstract In this work, we fabricated a metacomposite using magnetorheological fluid, in which Fe nanoparticles dispersed in silica gel spontaneously aligned under a magnetic field to form chain-like grids, thus working as a wire-grid polarizer. A single-layer polarizer was fabricated by mixing silica gel, silicone oil, high-purity spherical Fe powder with about 100 nm in diameter, followed by spin-coating and curing the mixture under a uniform magnetic field to form a solid matecomposite layer on a Teflon substrate. The polarizer was characterized by terahertz time-domain spectroscopy, showing good anisotropy and polarizing characteristics. Its performance was improved by multiple-layer stacking. The extinction ratio and degree of polarization of a five-layer polarizer are above 20 dB and 0.95 respectively in a frequency range of 0.8–2 THz.