3D-Printed Linear-Polarization Multiplexed Metasurface for Independent Terahertz Focusing and Orbital Angular Momentum Beam Generation
Dexian Yan, Zheng Wang, Xiangjun Li, L. Zhang, Jining Li
Abstract
We propose and experimentally demonstrate a dual-linear-polarization multiplexed metasurface capable of independently generating point-focused and focused orbital angular momentum (OAM) terahertz beams at 140 GHz. The metasurface consists of polymer-based birefringent meta-atoms fabricated via high-resolution 3D printing, enabling full 0–2<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pi$</tex-math></inline-formula> transmission phase control for both orthogonal polarizations through independent geometric parameter tuning. For y-polarized incidence, the device achieves a focal length of 82 mm with a high efficiency of 50.71%. For x-polarized incidence, it produces an focused OAM beam with a topological charge of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell$</tex-math></inline-formula> = –2 and a focal length of 115 mm, maintaining an efficiency of 54.61%. The measured focal positions, beam profiles, and phase structures exhibit strong agreement with full-wave simulations, with only minor deviations attributed to fabrication and measurement constraints. Compared with previously reported designs, the proposed all-resin structure offers simplified fabrication, single-layer multifunctional implementation, and high phase-control accuracy. This work demonstrates a scalable and low-cost strategy for multifunctional terahertz beam shaping and multiplexing, with promising applications in terahertz imaging, communication, and sensing.