Incident angle and temperature dependence of WSi wire-grid polarizer

• We examined the incident angle and thermal durability dependence on the WSi wire-grid polarizer.
• We formed the WSi grating (0.5 fill factor, 260 nm depth, and 400 nm period) on a Si surface.
• The WSi grating was formed using two beam interference method and dry etching.
• The extinction ratio of 22.2 dB at 2.5 μm wavelength was achieved at the θ = 40° incident angle.
• This wire-grid polarizer’s thermal resistance is higher than those of present infrared polarizers.

The dependences of the incident angle and thermal durability of a tungsten silicide (WSi) wire-grid polarizer were examined. A WSi grating with a 0.5 fill factor, 260 nm depth, and 400 nm period was formed on a Si surface using two-beam interference and dry etching. The TM transmission spectrum of the fabricated element was greater than 60% at the incident angle of θ = 40° (the angle between the incident direction and the perpendicular axis to the grating direction) in the 4–10 μm wavelength range. An extinction ratio of 22.2 dB was achieved at 2.5 μm wavelength. Additionally, results show that this polarizer has higher thermal resistance than that of commercial infrared polarizers. Therefore, this polarizer is effective for taking a polarized thermal image of high temperatures.