Ultra-wide band reflective metamaterial wave plates for terahertz waves

Terahertz (THz) electromagnetic waves have important applications in science and technology but available functional devices suffer from the issues of bulky size, low efficiency and narrow bandwidth. Here, based on Jones matrix and Poincar'e sphere analyses, we present a set of general criterions to help design high-efficiency ultra-wide band THz wave plates using ultra-thin reflective metamaterials. Two half-wavelength and one quarter-wavelength THz wave plates are designed and fabricated based on the general criterions, and their excellent polarization manipulation capabilities are demonstrated experimentally. In particular, the realized devices, with thicknesses similar to lambda/7, exhibit polarization-conversion efficiencies higher than 80% in ultra-wide working bandwidths (relative bandwidth >80% at about similar to 0.7 THz). Copyright (C) EPLA, 2017