Morphological dependence of all-dielectric terahertz metasurfaces

All-dielectric metasurface has been attractive attention in terahertz spectral range for low loss planar optical elements such as lens, beam splitter, waveplate, vortex plate, and magnetic mirror. Various shapes of meta-atoms are used in many studies, but no systematic comparison study between each shape has not been reported. In this work, we report the optical properties of various shapes of metasurfaces through finite difference time domain (FDTD) simulation. For pillar type all-dielectric metasurface, it is the area, not the detailed shape, of the cross section that determine the phase. Therefore, with the square lattice geometry, the square shape meta-atom shows best performance in terms of full phase control at the lowest pillar height with negligible polarization dependence.