Abstract
Although Polarization Modulation offers a high spectral efficiency, it has been not exploited much in modern communication systems because of the involvement of high switching speeds and complexity of associated hardware. We propose a dynamically controllable graphene metasurface capable to switch the polarization state of incident THz waves in real-time. The metasurface is designed by patterning two-dimensional graphene sheets with Fano-resonant chiral unit cells. Since the reflectance spectrum is characterized with co and cross polarized fields that bear asymmetric Fano line-shapes, several combinations of linear and elliptical polarization states are observed in a narrowband spectrum. At a fixed frequency, the electrostatic tunability property of graphene allows to switch between different polarization states by varying the chemical potential between 500 and 700 meV. The polarization state modulation with the proposed chiral graphene based metasurface is applied to implement a quaternary modulated digital communication system. Full-wave simulation results show the strong possibility of polarization modulation in THz communication systems. Graphene metasurfaces on account of the high electron mobility and discrete Fermi levels offer high switching speeds and seamless integration with digital systems.
Highlights
E LECTROMAGNETIC (EM) imaging/inversion schemes are used to obtain permittivity profile in an investigation domain using scattered fields that are measured away from the investigation domain [1], [2]
Note that this paper focuses on a deterministic EM inversion scheme, and the readers are referred [28], [29] and the references therein for more details on the Bayesian frameworks used for EM inversion
To discretize τ (r), N ref = 2500, which corresponds to an element length of ∆d = 0.15 m = λ/16
Summary
E LECTROMAGNETIC (EM) imaging/inversion schemes are used to obtain (complex) permittivity profile in an investigation domain using scattered fields that are measured away from the investigation domain [1], [2]. Version used for L2 - norm-constrained regularization and the thresholded version, often suffer from slow convergence which prohibits their direct application to electrically large investigation domains To overcome this bottleneck of slow convergence, a projected accelerated steepest descent (PASD) algorithm has been used to solve the three-dimensional (3D) EM inverse scattering problem [35]–[37]. Even with the increased rate of convergence, the computational cost of every iteration is still a limiting factor in applying the PASD scheme to electrically large investigation domains This high computational cost is a result of the matrix inversions required to compute the forward operator and its (first-order) Frechet derivative [35]. Numerical results demonstrate that the proposed scheme is more accurate and efficient than the existing CS-based EM inversion schemes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
