Wide-Band and High-Efficiency 90° Polarization Rotator Based on Tri-Layered Perforated Metal Films

Tri-layered metal films perforated with rectangle hole arrays of different orientations and separated by glass/air spacers have been studied theoretically and experimentally. The devices can rotate the polarization of the incident light by 90° with high efficiency and wide bandwidth in the near-infrared and microwave regions. The high-efficiency and wide bandwidth polarization rotation can be ascribed to the near-field coupling regime rather than the Fabry-Perot resonance according to the investigation of the difference between the two regimes.