Enhanced absorption of monolayer graphene using a metal–dielectric elliptical cavity array

Abstract

In this paper, a strong coupling system consisting of a metal–dielectric elliptical cavity array and graphene nanoribbons is demonstrated, which can effectively enhance the light absorption of monolayer graphene in the mid-infrared spectral region. The elliptical cavity excites a strong localized field, which facilitates strong coupling between a cavity mode and a graphene surface plasmon (GSP) mode, leading to ultrabroad Rabi splitting. The classical LC circuit model is used to reveal the resonance relationship of the cavity mode. The coupled harmonic oscillator model is used to confirm the strong coupling phenomenon. The numerical simulation results demonstrate that fluctuations can be effectively tuned by adjusting the filling factor of the graphene nanoribbons. In addition, the broadband absorption of monolayer graphene can be further enhanced by changing the mobility of the graphene. A bandwidth of 6 μm with an average broadband absorption rate of 78.8% is obtained for the monolayer graphene. Such a substantial enhancement in the broadband absorption of graphene can lead to high-performance graphene optoelectronic components in the mid-infrared spectral region.