Ultraviolet polarizer with a Ge subwavelength grating.

A polarizer with high extinction ratio (ER) was developed in the ultraviolet wavelength region using a germanium subwavelength grating (Ge-SWG). By utilizing an eigenmode with the Ge-SWG, a high ER was numerically predicted to exist without requiring a high structural aspect ratio. After using lithography to fabricate the proposed Ge-SWG, an experimentally high ER value of 17.4 dB was reached at a wavelength of 360 nm in the developed Ge-SWG, which had a very low structural aspect ratio of 1.67.