The terahertz(THz)vortex beam generators are designed and theoretically investigated based on single-layer ultra-thin transmission metasurfaces.Noncontinuous phase changes of metasurfaces are obtained by utilizing Pan...The terahertz(THz)vortex beam generators are designed and theoretically investigated based on single-layer ultra-thin transmission metasurfaces.Noncontinuous phase changes of metasurfaces are obtained by utilizing Pancharatnam-Berry phase elements,which possess different rotation angles and are arranged on two concentric rings centered on the origin.The circularly polarized incident THz beam could be turned into a cross-polarization transmission wave,and the orbital angular momentum(OAM)varies in value by lh.The l values change from±1 to±5,and the maximal cross-polarization conversion efficiency that could be achieved is 23%,which nearly reaches the theoretical limit of a single-layer structure.The frequency range of the designed vortex generator is from 1.2 THz to 1.9 THz,and the generated THz vortex beam could keep a high fidelity in the operating bandwidth.The propagation behavior of the emerged THz vortex beam is analyzed in detail.Our work offers a novel way of designing ultra-thin and single-layer vortex beam generators,which have low process complexity,high conversion efficiency and broad bandwidth.展开更多
Benefiting from the unprecedented superiority of coding metasurfaces at manipulating electromagnetic waves in the microwave band,in this paper,we use the Pancharatnam-Berry(PB)phase concept to propose a high-efficienc...Benefiting from the unprecedented superiority of coding metasurfaces at manipulating electromagnetic waves in the microwave band,in this paper,we use the Pancharatnam-Berry(PB)phase concept to propose a high-efficiency reflectivetype coding metasurface that can arbitrarily manipulate the scattering pattern of terahertz waves and implement many novel functionalities.By optimizing the coding sequences,we demonstrate that the designed 1-,2-,and 3-bit coding metasurfaces with specific coding sequences have the strong ability to control reflected terahertz waves.The two proposed1-bit coding metasurfaces demonstrate that the reflected terahertz beam can be redirected and arbitrarily controlled.For normally incident x-and y-polarized waves,a 10 d B radar cross-section(RCS)reduction can be achieved from 2.1 THz to5.2 THz using the designed 2-bit coding metasurface.Moreover,two kinds of orbital angular momentum(OAM)vortex beams with different moduli are generated by a coding metasurface using different coding sequences.Our research provides a new degree of freedom for the sophisticated manipulation of terahertz waves,and contributes to the development of metasurfaces towards practical applications.展开更多
Pancharatnam–Berry(PB)phase metasurface,as a special class of gradient metasurfaces,has been paid much attention owing to the robust performance for phase control of circularly polarized waves.Herein,we present an el...Pancharatnam–Berry(PB)phase metasurface,as a special class of gradient metasurfaces,has been paid much attention owing to the robust performance for phase control of circularly polarized waves.Herein,we present an element-based polarizer for the first step,which enables the incident electromagnetic waves into the cross-polarized waves with the relative bandwidth of 71%,and the polarization conversion ratio exceeds 90%at 6.9–14.5 GHz.Then an eight-elements coding polarizer based on the PB phase is presented for the applications on beam control and radar cross section reduction.The simulated values indicate that the reduction of radar cross section is more than 10 dB at 6–16 GHz.Our work reveals the availability of manipulating the waves,beamforming in communication systems and electromagnetic stealth,and so on.展开更多
基金the National Natural Science Foundation of China(Grant No.62071312)the Important R&D Projects of Shanxi Province,China(Grant No.201803D121083)the Shanxi Scholarship Council(Grant No.2020-135).
文摘The terahertz(THz)vortex beam generators are designed and theoretically investigated based on single-layer ultra-thin transmission metasurfaces.Noncontinuous phase changes of metasurfaces are obtained by utilizing Pancharatnam-Berry phase elements,which possess different rotation angles and are arranged on two concentric rings centered on the origin.The circularly polarized incident THz beam could be turned into a cross-polarization transmission wave,and the orbital angular momentum(OAM)varies in value by lh.The l values change from±1 to±5,and the maximal cross-polarization conversion efficiency that could be achieved is 23%,which nearly reaches the theoretical limit of a single-layer structure.The frequency range of the designed vortex generator is from 1.2 THz to 1.9 THz,and the generated THz vortex beam could keep a high fidelity in the operating bandwidth.The propagation behavior of the emerged THz vortex beam is analyzed in detail.Our work offers a novel way of designing ultra-thin and single-layer vortex beam generators,which have low process complexity,high conversion efficiency and broad bandwidth.
基金Project supported by the National Natural Science Foundation of China(Grant No.61865008)Northwest Normal University Young Teachers’Scientific Research Capability Upgrading Program(Grant No.NWNU-LKQN2020-11)the Scientific Research Fund of Sichuan Provincial Science and Technology Department,China(Grant No.2020YJ0137)。
文摘Benefiting from the unprecedented superiority of coding metasurfaces at manipulating electromagnetic waves in the microwave band,in this paper,we use the Pancharatnam-Berry(PB)phase concept to propose a high-efficiency reflectivetype coding metasurface that can arbitrarily manipulate the scattering pattern of terahertz waves and implement many novel functionalities.By optimizing the coding sequences,we demonstrate that the designed 1-,2-,and 3-bit coding metasurfaces with specific coding sequences have the strong ability to control reflected terahertz waves.The two proposed1-bit coding metasurfaces demonstrate that the reflected terahertz beam can be redirected and arbitrarily controlled.For normally incident x-and y-polarized waves,a 10 d B radar cross-section(RCS)reduction can be achieved from 2.1 THz to5.2 THz using the designed 2-bit coding metasurface.Moreover,two kinds of orbital angular momentum(OAM)vortex beams with different moduli are generated by a coding metasurface using different coding sequences.Our research provides a new degree of freedom for the sophisticated manipulation of terahertz waves,and contributes to the development of metasurfaces towards practical applications.
基金supported by the National Natural Science Foundation of China(No.42274189)the Project of Science and Technology of Shaanxi(No.2021JM-395).
文摘Pancharatnam–Berry(PB)phase metasurface,as a special class of gradient metasurfaces,has been paid much attention owing to the robust performance for phase control of circularly polarized waves.Herein,we present an element-based polarizer for the first step,which enables the incident electromagnetic waves into the cross-polarized waves with the relative bandwidth of 71%,and the polarization conversion ratio exceeds 90%at 6.9–14.5 GHz.Then an eight-elements coding polarizer based on the PB phase is presented for the applications on beam control and radar cross section reduction.The simulated values indicate that the reduction of radar cross section is more than 10 dB at 6–16 GHz.Our work reveals the availability of manipulating the waves,beamforming in communication systems and electromagnetic stealth,and so on.
