Dynamically tunable plasmon-induced absorption in resonator-coupled graphene waveguide

Abstract

We demonstrate plasmon-induced absorption (PIA) in an ultra-compact graphene waveguide system which is composed of a single graphene sheet with two air cavities side-coupled to a graphene nanoribbon. By designing two coherent optical pathways, the pronounced PIA can be achieved due to the extreme destructive interference between the radiant and subradiant modes supported by the two graphene nanoribbons. The resonant strength shows strong dependence on the coupling distance between the two graphene nanoribbons and the resonance wavelength can be dynamically tuned by varying their Fermi energy. Furthermore, the group delay time up to −0.14 ps can be reached at the PIA window, suggesting unique fast-light feature. In addition, the double PIA phenomenon is also analyzed by introducing another graphene nanoribbon. Our results may pave the way for controlling the transmission of a light signal in the design of ultra-compact plasmonic devices.