Theoretical study on generation of radially polarized beam from linearly polarized beam with all-silicon metasurface in the terahertz regime

A transmissive all-silicon dielectric square metasurface with a side length of 12.4 mm is designed in this paper. At 2.52 terahertz, the normally incident x-polarized Gaussian beam can be shaped into the radially polarized narrow-width annular beam with Bessel-Gaussian amplitude distribution at a propagation distance of 45 mm away from the metasurface. Anisotropic rectangular silicon pillars with different dimensions and rotation angles are arranged on the silicon substrate to manipulate the beam. To suppress the reflection loss, a polarization-independent square silicon pillar array is also proposed, which is patterned at the other side of the substrate. In addition, the errors analysis is also discussed. It is expected that our study may have potential for applying terahertz wave in high-resolution microscopy and capturing particles in three dimensions.

Automated summary

In this study, a transmissive all-silicon dielectric square metasurface was designed to manipulate the incident beam into a radially polarized narrow-width annular beam with Bessel-Gaussian amplitude distribution. Anisotropic rectangular silicon pillars and a polarization-independent square silicon pillar array were used to control and suppress reflection loss of the beam. The study may have potential applications in high-resolution microscopy and three-dimensional particle capture using terahertz waves.