Ultrathin Terahertz Planar Lenses
  Conventional optical components shape the wavefront of propagating light by adjusting the optical path length, which requires the use of rather thick lenses, especially for the adjustment of terahertz (THz) radiation due to its long wavelength. Two ultrathin THz planar lenses were designed and fabricated based on interface phase modulation of antenna resonance. The lens thicknesses were extremely reduced to 100 nm, which is only 1/4000th of the illuminating light wavelength. The focusing and imaging functions of the lenses were experimentally demonstrated. The ultrathin optical components described herein are a significant step toward the development of a micro-integrated THz system. 
Dan Hu, Xinke Wang, Shengfei Feng, Jiasheng Ye, Wenfeng Sun, Qiang   Kan, Peter J. Klar, and Yan Zhang
physics.optics