Conventional approach to change the polarization state oflightis to use a birefringent crystal which can cause different phase delays along two orthogonal axes. Yet this approach may have some disadvantages such as low efficiency, bulky volume, frangibility, long propagation distance and narrow bandwidth.Controlling the polarization state of THz wave remains a big challenge due to lack of suitable natural materials.Metasurfaces, a kind of two-dimensional artificially designedmaterials,offera new way to study novel terahertz devices.
Professor JinsongLiuledgraduatestudent WeichengMoand othersinlaser and terahertz functional laboratoryofWuhanOptoelectronics National Laboratory achieveda terahertz polarization converterworking at 0.1THz based on metasurfaces.Firstly, the simulation presents amethod toflexiblycontrolthepolarizationof THz wave.This metasurface consists of A line arrays and B line arrayswhich can control Eyand Exrespectively. A and B are interlaced arrangement along y direction with an offset distance d between them in the x directionwhich can cause the abrupt phase delay betweenbeamA and B, so as to tune the polarization of the reflected wave freely.Then several samples are madevia the photolithography and electron beam evaporation technology. Ahalf wave plateis obtainedin the experiment,provingthe feasibility of the method.Polypropylene spacer is usedto make themetasurface very flexibleand ismore suitable for future applications.
This work”Ultrathinflexibleterahertzpolarizationconverterbasedonmetasurfaces”is reported on Optics Express (Vol. 24,no.12, pp. 13621-13627,2016)of OSA onJune 16, 2016. This research is funded byNational Natural Science Foundation of China(501100001809and the Wuhan Applied Basic research project,China(20140101010009).).
（a）The structure of the terahertz polarization converter（b）The Lissajous Figure of the reflected wave
