Ultra-broadband high-efficiency cross-polarization conversion and amplitude-phase manipulable multi-functional wavefront manipulation based on terahertz metasurface

Drawing upon the physical phenomenon of polarization transformation, this paper proposes an ultra-broadband, high-efficiency linear polarization converter composed of a metallic grating, an L-shaped metallic patch, and a dielectric substrate. The polarization conversion properties have been scrutinized using the finite element numerical simulation software CST. The computational outcomes reveal that the polarization converter operates within the frequency range of 0.5 THz to 1.8 THz, exhibiting a relative bandwidth of 113%, a transmission coefficient exceeding 0.87, a polarization conversion efficiency approaching 100%, and a phase coverage spanning 360 degrees. Furthermore, a Fabry-Perot interference model was established utilizing Matlab to corroborate the concurrence between the theoretical analysis and the numerical findings. The polarization converter metasurface amalgamates both phase and transmission amplitude variations to accomplish not only a two-dimensional focusing lens operating between 1.55 THz and 1.65 THz, but also a spatial imaging capability utilizing transmission amplitude variation within the 0.5 THz to 1.15 THz range. The outcomes demonstrate that the devised metasurface exhibits ultra-broadband and high transmission efficacy, thus providing novel insights for the versatility of terahertz wave polarization and phase manipulation.