太赫兹辐射
石墨烯
光学
涡流
太赫兹超材料
物理
超材料
光电子学
材料科学
远红外激光器
激光器
量子力学
热力学
作者
Anas S. Zainud-Deen,Hend A. Malhat,Abdel-Razik Sebak,Mona M. Badawy
标识
DOI:10.1007/s11082-024-06994-4
摘要
Abstract This paper investigates the generation of orbital angular momentum vortex beams using a graphene metasurface in the terahertz frequency band. The proposed design consists of 20 × 20 unit-cell elements to operate in 1.2 THz applications. Each element is a graphene ring patch printed on a silicon dioxide substrate backed with a polysilicon ground plane of size 75 × 75 × 25 µm 3 . The graphene reconfigurable surface conductivity is used to control the beam shape, direction, and directivity radiated from the metasurface, through the application of DC biasing voltages. A parametric study on the effect of graphene chemical potential, relaxation time and temperature on the unit-cell reflection properties is introduced. The reflection magnitude varies from − 2.1 dB to -0.8 dB with a 350-degree phase variation for µ c ranging from 0.25 eV to 1.6 eV at $$\tau$$ =5 ps, and T = 300 K. The effect of graphene relaxation time from 0.3 ps to 10 ps on the reflection coefficient at µ c = 0.7 eV, and T = 300 K is investigated. The metasurface radiation characteristics are investigated under the illumination of two types of incidence sources, plane-wave, and focused-waves. A depiction of a single vortex beam in various orientations θ = 0, 30 o , 50 o , and 70 o , φ = 90 o for l = 1 is presented. The purity of the OAM single beam shows that 94% of the power is concentrated in the designed mode. A graphene metasurface can to convert linearly polarized input into multiple beams exhibiting orthogonal modes. Two/four vortex beams in different directions are demonstrated. The capacity for wireless communication in the terahertz band can be enhanced by utilizing a graphene metasurface.
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