Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to...Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to its characteristic of infinitely orthogonal modes.However,traditional methods generating OAM beams are bound to complex structure,large device,multiple layers,complex feed networks,and limited beams in microwave range.Here,a digital coding transmissive metasurface(DCTMS)with a single layer substrate and the bi-symmetrical arrow is proposed and designed to generate multi-OAM-beam based on Pancharatnam–Berry(PB)phase principle.The 3-bit phase response can be realized by encoding the geometric phase into rotation angle of unit cell for DCTMS.Additionally,the phase compensation of the metasurface is introduced to achieve the beam focusing and the conversion from spherical wave to plane wave.According to the digital convolution theorem,the far-field patterns and near-field distributions of multi-OAM-beam with l=–2 modes are adequately demonstrated by DCTMS prototypes.The OAM efficiency and the purity are calculated to demonstrate the excellent multiOAM-beam.The simulated and experimental results illustrate their performance of OAM beams.The designed DCTMS has profound application in multi-platform wireless communication systems and the multi-channel imaging systems.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62171460 and 61801508)the Natural Science Basic Research Program of Shaanxi Province,China(Grant Nos.2020JM-350,20200108,and 20210110)+3 种基金the Young Innovation Team at Colleges of Shaanxi Province,China(Grant No.2020022)the Postdoctoral Innovative Talents Support Program of China(Grant No.BX20180375)China Postdoctoral Science Foundation(Grant Nos.2021T140111,2019M650098,and 2019M653960)the Postdoctoral Research Funding of Jiangsu Province(No.2019K219).
文摘Orbital angular momentum(OAM)is a phenomenon of vortex phase distribution in free space,which has attracted enormous attention in theoretical research and practical application of wireless communication systems due to its characteristic of infinitely orthogonal modes.However,traditional methods generating OAM beams are bound to complex structure,large device,multiple layers,complex feed networks,and limited beams in microwave range.Here,a digital coding transmissive metasurface(DCTMS)with a single layer substrate and the bi-symmetrical arrow is proposed and designed to generate multi-OAM-beam based on Pancharatnam–Berry(PB)phase principle.The 3-bit phase response can be realized by encoding the geometric phase into rotation angle of unit cell for DCTMS.Additionally,the phase compensation of the metasurface is introduced to achieve the beam focusing and the conversion from spherical wave to plane wave.According to the digital convolution theorem,the far-field patterns and near-field distributions of multi-OAM-beam with l=–2 modes are adequately demonstrated by DCTMS prototypes.The OAM efficiency and the purity are calculated to demonstrate the excellent multiOAM-beam.The simulated and experimental results illustrate their performance of OAM beams.The designed DCTMS has profound application in multi-platform wireless communication systems and the multi-channel imaging systems.
