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

• We fabricated an infrared wire-grid polarizer with an antireflection grating structure using direct imprint lithography on a chalcogenide glass.
• We formed the Al grating (0.7 fill factor, 100 nm thickness, and 500 nm period) by depositing Al obliquely on the grating.
• The transverse magnetic transmittance of the fabricated polarizer was over 70% in the 8.5–10.5 μm wavelength range.
• The TE transmittance of the fabricated element was around 1% in the 2.5−12 μm wavelength range.

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.