Experimental Mid-Infrared Absorption (84%) of Single-Layer Graphene in a Reflective Asymmetric Fabry–Perot Filter: Implications for Photodetectors

There is a growing interest toward graphene and 2D materials for their exceptional geometrical, optical, and electronic features, which make them unique for photonic and optoelectronic applications. Achieving extraordinarily high absorption by the electric field enhancement on a single atomic plane is a challenging goal for physics and for many of the abovementioned uses. We demonstrate here experimentally for the first time a great enhancement absorption on a large (1 in.) optical device based on single-layer chemical vapor deposition graphene (SLG) by exploiting the electric field inside an asymmetric Fabry–Perot resonator fabricated by radio frequency sputtering. In such a filter, graphene absorption of 84% peaked at 3150 nm is obtained, in very good agreement with COMSOL Multiphysics calculations. Absorption intensity and bandwidth are modeled as a function of the incident angle of the electromagnetic radiation, and the optical constants of SLG are obtained as a function of Fermi energy. The Raman spectrum measured on the SLG in the Fabry–Perot cavity proves the effectiveness of the fabrication method in preserving graphene's physical properties. Our results disclose exciting potentialities for building visible and infrared optical light-absorbing devices based on 2D materials.