Cylindrical vector beams (CVBs), being a special kind of beams with spatially variant states of polarizations, are promising in photonics applications, including high-resolution imaging, plasmon excitation, optical trapping, and laser machining. Recently, generating CVBs using metasurfaces has drawn enormous interest owing to their highly designable, multifunctional, and integratable features. However, related studies remain unexplored in the terahertz regime. Here, a generic method for efficiently generating terahertz CVBs carrying orbital angular momentums (OAMs) is proposed and experimentally demonstrated using transmission-type spatial-variant dielectric metasurfaces, which is realized by designing the interference between the two circularly polarized transmission components. This method is based on spin-decoupled phase control allowed by simultaneously manipulating the dynamic phase and geometric phase of each structure, endowing more degree of freedom in designing the vector beams. Two types of metasurfaces which respectively generate polarization-dependent terahertz vector vortex beams (VVBs) and vector Bessel beams (VBBs) are experimentally characterized. The proposed method opens a new window to generate versatile vector beams, providing new capabilities in developing novel, compact, and high-performance devices applicable to broad electromagnetic spectral regimes.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): URF-2950-CRG5, CRF-2016-2950-RG5, CRF-2017-3427-CRG6)
Acknowledgements: This research was funded by the National Natural Science Foundation of China (Grant Nos. 61605143, 61735012, 11974259, 61705167, 61875150, and 61420106006); Tianjin Municipal Fund for Distinguished Young Scholars (grant No. 18JCJQJC45600); Scientific Research Project of Tianjin Education Commission (Grant No. JWK1608); Start-up project of scientific research of Tianjin University of Technology and Education (Grant No. KYQD1718); Guangxi Key Laboratory of Automatic Detecting Technology and Instruments (YQ17203, YQ18205); King Abdullah University of Science and Technology, Office of Sponsored Research (Grand Nos. URF-2950-CRG5, CRF-2016-2950-RG5, and CRF-2017-3427-CRG6).