Fabrication of an infrared wire-grid polarizer via anisotropical Si etching in KOH solution

Abstract

An infrared wire-grid polarizer was fabricated using two-beam interference lithography, anisotropical etching of Si in KOH solution, and thermal evaporation of Al. Consequently, an infrared wire-grid polarizer with a 1-µm-pitch and 195-nm-thick Al grating could be fabricated on the Si grating. The transmittance of transverse magnetic polarization was greater than 48% at 10-µm wavelength, and the extinction ratio was over 22 dB at this wavelength. This polarizer can be fabricated at a much lower cost and using simpler fabrication processes compared to those for conventional infrared polarizers fabricated using dry etching.