Near-Infrared Polarizer with Tungsten Silicide Wire Grids

We fabricated a near-infrared wire-grid polarizer consisting of a 230-nm-pitch tungsten silicide (WSi) grating on a SiO2 substrate using two-beam interference lithography and dry etching. The transverse magnetic (TM) polarization transmittance of the fabricated polarizer exceeded 80% in the 1000–1600-nm wavelength range. The extinction ratio was higher than 20 dB in the 650–1500-nm wavelength range. We also measured the extinction coefficient κ of WSi and verified that WSi is a suitable polarizing material in the near-infrared range.