Modeling and imprint fabrication of an infrared wire-grid polarizer with an antireflection grating structure

An infrared wire-grid polarizer with an antireflection (AR) grating structure was fabricated using direct imprint lithography on both sides of a low toxicity chalcogenide glass (Sb–Ge–Sn–S system) simultaneously. The AR grating structure was designed using rigorous coupled-wave analysis theory. Silicon carbide with a grating period of 500 nm and glassy carbon with a grating period of 3 μm were employed as molds. After imprinting, a wire-grid polarizer was made by depositing Al obliquely on the grating. The transverse magnetic (TM) transmittance of the fabricated polarizer was over 70% at 8.5–10.5 μm wavelength, although the transmittance of the glass substrate is 62–66%, and the extinction ratio was over 20 dB at 11 μm wavelength. The polarizer has a high TM transmittance and is cheaper and simpler to fabricate as compared with conventional infrared polarizers.