Broadband and wide angle infrared wire-grid polarizer.

ABSTRACT

An infrared polarizer consisting of metal-insulator-metal (MIM) gratings is designed with transmittance exceeding 85% and polarization extinction ratio (ER) higher than 70 dB in the wavelength range from 1.5 to 8 µm. Moreover, the polarizer retains excellent performance even when the incident angle increases to as large as 80°. The MIM gratings support magnetic polariton (MP) in the near-infrared regime and operate non-resonantly in the mid-infrared regime, both of which result in the advantages of high extinction ratio, broadband, and wide angle. The proposed structure can find applications in polarizer, beam-splitter, filter, and isolator in the infrared range.