Infrared polarizer employing multiple metal-film subwavelength gratings.

A multiple thin metal-film subwavelength grating is proposed for polarizers in the infrared wavelength region of 10-20 μm. The dependence of the transmission characteristics of the polarizers on structural parameters was obtained numerically, and the potential for high performance was confirmed experimentally. The measured TE-wave losses in a polarizer comprising a triangular triple Al-film grating are more than 45 and 35 dB for the wavelength ranges of 10-16 and 16-20 μm, respectively, while the net TM-wave losses are lower than 1.5 dB in the wavelength rage of 15-20 μm.