Abstract
Orbital angular momentum (OAM) generation based on metasurfaces has attracted tremendous interest due to its potential in capacity enhancement of high-speed wireless communication systems. Reconfigurability is one of the key desired characteristics for the design of future metasurfaces. In this paper, a metasurface taking advantage of vanadium dioxide (VO2) is proposed. The proposed design can generate a non-diffractive OAM beam and achieve the multiple reconfigurability of the topological charge, beam radius, beam deflection angle. The operation frequency can be adjusted by controlling the state of VO2 at terahertz (THz) region. Simulation results demonstrate that the designed metasurface can generate a non-diffractive OAM beam with tunable topological charge and beam radius, propagating along ± x or ± y directions with the controllable deflection angle between 6.74° and 44.77°, ranging from 0.69 THz to 0.79 THz.
Highlights
Electromagnetic (EM) waves have been demonstrated to carry angular momentum (AM), encompassing spin angular momentum (SAM) and orbital angular momentum (OAM) [1]–[3]
We verify that the metasurface can be engineered to deflect the beam at the desired angle. We investigate this using an OAM beam with l = +4 propagating along the +y or −y direction with |θt | = 6.74°, 13.58°, and 44.77° modeled by superimposing Equation (4) and (7)
We model a non-diffractive OAM beam with l = +4 and β = 20° propagating along the +y direction with θt = 13.58◦ making use of Equation (8)
Summary
Electromagnetic (EM) waves have been demonstrated to carry angular momentum (AM), encompassing spin angular momentum (SAM) and orbital angular momentum (OAM) [1]–[3]. Previous research has mainly focused on producing OAM beams based on metasurfaces without tunable metaparticles The majority of these metasurfaces are aimed at producing an OAM beam with a particular l [15], [16]; realizing multichannel superpositions of OAM states with various l values [17], [18]; or generating OAM beams with different topological charges at different wavelengths [19], [20], input beam intensities [21] and polarization states [22]. This study can be used for the realization of software-defined wideband reconfigurable metasurfaces for THz applications
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