Enhancement of THz absorption in monolayer graphene for light at Brewster angle incidence

Abstract

• A tunable THz graphene absorber is proposed and investigated. • Above 50% resonant absorption is achieved for light at Brewster angle incidence. • The absorption performance can be tuned and extended to multichannel. The enhancement of absorption in graphene for light at Brewster angle incidence is investigated. It is achieved by placing a graphene on a resonant Brewster filter that incorporating a spacer layer. The absorber presents above 50% absorption at resonance, which is attributed to the excitation of guided mode resonances. The electromagnetic field intensity distributions are illustrated to intuitively confirm the physical mechanism of such phenomenon. Moreover, the influence of geometric parameters on absorption is investigated to provide a useful guidance for practical fabrication. Besides, it is found that the absorption properties not only can be controlled by adjusting the incident angle but also can be dynamically tuned by changing the Fermi level. Last, the graphene absorption can be easily extended to multichannel by only an increase in the thickness of spacer. The results open new avenues for combining graphene with general guided mode resonance structure to enable novel optoelectronics device applications.