▎ 摘　　要

A novel triple-band, tunable, high-efficiency, mid-infrared reflected cross-polarization converter based on a graphene metasurface is proposed and studied, which comprised a periodic ellipse graphene patch with a slit, a dielectric spacer, and a metal gold substrate. Numerical simulations indicate that the proposed converter can convert a linearly polarized wave to its cross-polarized wave at three resonance frequencies due to the superimposition of the two reflected components with a near 180 degrees or 0 degrees phase difference. The polarization conversion ratios of the three bands are 98.29%, 98.42%, and 97.64%, respectively. The polarization converter can be dynamically tuned by changing the Fermi energy. Our proposed tunable polarization converter has great potential in the application of electromagnetic polarization control. (C) 2020 Optical Society of America