Fabrication of a reflective polarization wavelength filter via anodization of a Ti grating film

A reflective-type polarization wavelength filter was fabricated by anodizing a Ti grating film. This polarization filter consisted of a Ti film, an anodized titanium oxide film (thickness ∼25nm), and a photoresist grating with a pitch of 410 nm. The reflectance was less than 10% for both polarizations at 490-675 nm at an incident angle of 9°. In addition, the transverse electric (TE) reflectance of the fabricated element was over 40%, whereas the transverse magnetic (TM) reflectance was 25.8% at 375 nm. Upon increasing the incident angle to 75°, the TE reflectance increased to 77.8% at 375 nm, whereas the TM reflectance decreased to 5.9%.