Mid-infrared wire-grid polarizer with silicides

An infrared (IR) polarizer with tungsten silicide (WSi) wire grid was fabricated by two-beam interference exposure and reactive ion etching. To enhance TM transmittance, silicon monoxide was deposited between the WSi wire grid (400 nm period) and a Si substrate. The transmittance was over 80% in the 4-5 mu m wavelength range. The ratio of TM and TE transmittances was over 100 (20 dB) in the 2.5-6 mu m wavelength range. The fabricated polarizer has higher durability and bettter compatibility with microfabrication processes compared with conventional IR polarizers. (C) 2008 Optical Society of America.