Terahertz Beam Shaping: Gaussian to Flat-top Beam Conversion Through Tri-layer Metasurface

Abstract

A flat-top beam is preferred to a normal Gaussian beam for various imaging applications since it provides more uniform illumination over a scene. In this paper, we present a highly efficient tri-layer metasurface lens for terahertz beam shaping, namely Gaussian to flat-top beam conversion. This metasurface includes linear polarization conversion, and a full 2π phase tunability range can be covered by varying the geometry of anisotropic resonators. The required phase profile of the metasurface lens is obtained through the Gerchberg–Saxton (GS) algorithm. Full-wave simulations and analytical results confirm that the incident Gaussian beam is transformed to a flat-top beam.