Broadband infrared polarizer of graphene wire grids with flat PER curves

Since 2004, the flourishing two-dimensional graphene has sparked extensive research on graphene-based optical and optoelectronic devices with high performance due to its ultra-fast photoelectric response, broadband, and tunable optical response. However, up until now, graphene-based wire grid polarizers have not been demonstrated to perform excellent characteristics with flat polarization extinction ratio (PER) curves, while they all exhibited narrow peak-shaped working bands. Here, we propose a broadband polarizer based on graphene wire grids with a flat PER curve of up to ∼84.5 dB in the ultrawide range of 1–10 μm. In the range of <4 μm, the graphene wire grid polarizer exhibits a strong plasmon resonance effect and outputs a linear-polarized state. Its performance is closely related to carrier density that is tuned by the Fermi level (EF) and thickness of graphene.