High-performance dual-band graphene absorbers in the near-infrared range

Abstract

The inherent limitations of monolayer graphene, specifically its low optical absorption and lack of spectral selectivity, significantly restrict its application in advanced optoelectronic devices. To overcome these challenges, this study proposes a novel absorber structure consisting of metal, dielectric, and metal layers coupled with graphene. This configuration greatly enhances the interaction between incident light and the graphene material. Initially, two individual absorbers were designed for specific wavelengths and subsequently integrated into a comprehensive dual wavelength band structure. This integrated design achieves a total absorption rate exceeding 99% at both the 1 μm and 2 μm target wavelengths. Concurrently, the graphene layer specifically contributes 32.8% and 21.6% to the absorption at these respective wavelengths. To efficiently optimize complex structural variables, an iterative method was introduced, which drastically reduces the required computational effort. Ultimately, the proposed design boosts the absorption capability by a factor of 10 to 15 compared to bare monolayer graphene. This research provides a highly promising and efficient approach for developing high performance nanophotonic devices.