Cross-polarization conversion with periodic perforated silver film in the near-infrared spectral range

An enhanced polarization rotation of the zero-order transmission in the near-infrared spectral range is realized by using a silver film with an array of perforated normal and oblique rectangular holes. The ellipticity is small when the phase difference between Ex and Ey components approaches to π, and the transmitted field is nearly linear polarized within a wide spectral range. The polarization of transmitted field is determined by the intensity ratio between x and y components of electric field, which is modified by manipulating the incident wavelength or the incident polarization. Without changing the geometry parameters, one can get any desired rotation angle using the designed structure. In addition, the transmission is strong, and the designed structure can be used as a subwavelength half wave plate.