Dual-band tunable mid-infrared polarization converter based on U-shaped graphene metamaterial

A dual-band tunable mid-infrared reflective polarization converter using graphene metamaterial is proposed. The converter is composed of a periodically U-shaped graphene sheet, a dielectric layer, and a metal layer from top to bottom. It is able to effectively reflect and convert a linear polarized incidence mid-infrared wave to its cross polarization reflected wave at the two resonant frequencies with the polarization conversion ratio (PCR) approaching 100%. The proposed polarization converter possesses great potential applications in mid-infrared, antenna, spectroscopy, radiometer, thermal testing instrument, and remote sensor.