Terahertz broadband band-stop filter based on metasurface

The metasurface is an ultra-thin two-dimensional array of planar device composed of periodic meta-units to enable multi-functional and extraordinary electromagnetic control, and thus shows great potentials in many scientific and technical applications due to its excellent filtering characteristics when used as filters. For most applications, the filter bandwidth is one of the most important performance metrics. In this paper, we demonstrate a broadband terahertz band-stop filter based on the design principle of metasurface. By superposition of multi-layer metasurfaces and the interactive couplings in-between, the designed filter demonstrates a significantly broadened bandwidth and the stop-band rejection with excellent cut-off in the range of 373-502GHz. The result reveals the mechanism of bandwidth broadening through field distribution in the full-wave analysis by finite element simulation. Further study also reveals absolute polarization independence of the designed metasurface filter, i.e. exactly the same transmission spectra for TE or TM incidence.