High-efficiency, p-suppressing, infrared reflection polarizers that employ a high-index transparent thin film on a low-index transparent substrate are described. Examples are given of such polarizers using infrared-transparent semiconductor films of Ge and Si on Irtran and glass substrates at the 2.8 μm (HF) and 3.8 pm (DF) laser wavelengths. The unextinguished power reflectance for the s polarization is high, as Z95 %, and is comparable to that of thin-film reflection polarizers that use metallic substrates. The effect of small changes (or errors) of film thickness, angle of incidence and wavelength on the extinction ratio of the device is also considered. Because of the high efficiency of the single-reflection polarizer, two, three or four such elements can be cascaded to achieve (1) parallelism or collinearity of the input and output beams, and (2) very low extinction ratio for the compound polarizer, while maintaining appreciable throughput for the passed (s) polarization component.