Xinfei Wu, Manna Gu, Huizhen Feng, Shuaikang He, Dong Li, Ying Tian, Bo Fang, Le Wang, Zhi Hong & Xufeng Jing
Wu et al. (2025)
Photonics Research 13, 2744 · placeholder image
Research overview
This paper demonstrates vector vortex beams whose topological charge changes along the direction of propagation at 0.1 THz, using all-dielectric metasurfaces 3D printed in aluminium oxide. Each 45 × 45 element metasurface (1.6 mm period, 2.5 mm pillars) combines focusing with polarization-dependent phase control. Under left-circular illumination the topological charge steps from +3 to −3, and under right-circular illumination from +4 to −4, across focal planes from 22 mm to 42 mm. The measured focusing efficiencies were 26.7% and 29.6%, compared with 37.6% and 38.5% in simulation. Simulation and experiment agree to within 6%. A linear polarizer in front of the THz camera separated the polarization components to characterise the vector modulation.
Key findings
- Vector vortex beams with topological charge changing along propagation at 0.1 THz
- Charge steps from +3 to −3 (LCP) and +4 to −4 (RCP) between 22 mm and 42 mm
- All-dielectric Al₂O₃ metasurfaces made by 3D printing (SLA)
- Measured focusing efficiencies of 26.7% and 29.6%; experiment within 6% of simulation
