A Polarizer Using Thin Metallic-Film Subwavelength Grating for Infrared to Terahertz Region

A polarizer using a sinusoidal or triangular thin metallic-film subwavelength grating is proposed. The dependence of polarizer transmission characteristics on structural parameters of the grating was obtained numerically, and its potential for high performance was confirmed experimentally. The measured transmission loss for the TE-waves with a 25 nm-thick gold-film grating with a triangular profile was higher than 50 dB while the corresponding transmission loss for the TM-waves was lower than 1 dB in the frequency range of 1.0-2.5 THz. The metallic subwavelength grating structure has demonstrated its potential as a low-loss, high-extinction ratio, wide-aperture, and robust polarizer for the infrared and terahertz regions.