Circular Polarizer Realized by a Single Layer of Planar Chiral Metallic   Nanostructure
  As a basic optical element, circular polarizer plays significant roles in signal transmission, measurements and life science microscopy. Three-dimensional (3D) chiral structures have been thought to be necessary to realize circular polarizers. Here we demonstrate theoretically and experimentally for the first time that a high-efficiency circular polarizer could be realized by a single layer of planar 2D chiral structure. Our proposed circular polarizer is based on unidirectional polarization conversion instead of circular polarization stop bands. Since two-dimensional planar structures present obvious advantage for fabrication and integration on chip, the proposed circular polarizer is of great interest in integrated optics and microscopy. It provides a novel scheme to manipulate polarizations of light wave, as well as Terahertz wave and microwave. 
Weimin Ye, Xiaodong Yuan, Chucai Guo, Jianfa Zhang, Biao Yang, Ken   Liu, Zhihong Zhu, Chun Zeng
physics.optics