Broadband tunable multi-functional polarization converter based on a graphene metasurface
Saman Heidari, Najmeh Nozhat
Abstract
In this paper, a tunable multi-functional polarization converter based on a graphene metasurface has been designed. For the chemical potential of 1 eV, the structure has a polarization conversion ratio higher than 0.9 in the frequency range of 8.08 to 8.29 THz and also in the wide frequency range of 10.28 to 12.56 THz. Therefore, broadband linear to linear polarization conversion has been obtained. Also, in four frequency ranges, linear to circular polarization conversion has been realized. In addition to linear to linear and linear to circular functions, the structure also has circular to linear and circular to circular polarization conversion capabilities. The effects of chemical potential, geometrical parameters, and incident and polarization angles on the polarization conversion performance have been investigated. By changing the chemical potential, the reflected wave switches between different polarizations. Moreover, the results show that polarization conversion is insensitive to the incident angle up to 40°. The physical mechanism and analytical methods of multiple interference theory and equivalent circuit model for the suggested polarization converter have been presented. The presented structure with appropriate features such as different polarization conversions, adjustability, switching capability between different polarizations, broad bandwidth, good incident angle stability, and simple construction has many applications in communication, biological detection, imaging, and sensing.