Dynamically Tunable and Multifunctional Polarization Beam Splitters Based on Graphene Metasurfaces

Abstract

Based on coupled-mode theory (CMT) and the finite-difference time-domain (FDTD) approach, we propose a graphene metasurface-based and multifunctional polarization beam splitter that is dynamically tunable. The structure, comprising two graphene strips at the top and bottom and four triangular graphene blocks in the center layer, can achieve triple plasma-induced transparency (PIT). In a single polarization state, the computational results reveal that synchronous or asynchronous six-mode electro-optical switching modulation may be performed by modifying the Fermi levels of graphene, with a maximum modulation degree of amplitude (MDA) of 97.6% at 5.148 THz. In addition, by varying the polarization angle, a polarization-sensitive, tunable polarization beam splitter (PBS) with an extinction ratio and insertion loss of 19.6 dB and 0.35 dB at 6.143 THz, respectively, and a frequency modulation degree of 25.2% was realized. Combining PIT with polarization sensitivity provides a viable platform and concept for developing graphene metasurface-based multifunctional and tunable polarization devices.

Recent Advances in Reconfigurable Metasurfaces: Principle and Applications

“…In Figure 4 d [ 190 ], Xiao et al proposed a polarization beam splitter (PBS) based on a graphene metasurface composed of a triple-layer metamaterial made up of two graphene strips and four graphene blocks. When under y -polarized illumination, this metasurface performs as an optical switch at six different frequencies in the terahertz band when changing the Fermi levels of graphene on the metasurface.…”

High-Sensitivity Sensor Based on Diametrical Graphene Strip Plasma-Induced Transparency

“…Moreover, it is inconvenient to adjust the geometric parameters of the metallic material pattern layer once the device is fabricated. Meanwhile, this method has the obvious drawback that the PIT peak is shifted as the structure is adjusted, which hinders the practical application effect of bright-bright mode coupled PIT in filters and modulators [20][21][22]. To address this problem, graphene, an emerging two-dimensional material composed of honeycomb carbon atoms, has been proposed to design tunable PIT devices because its plasmonic response can be actively tuned by a controlled graphene chemical potential [23][24][25][26].…”