Transmission properties and molecular sensing application of CGPW

In this paper, a cylindrical graphene plasmon waveguide (CGPW), which consists of two rolled graphene ribbons, a dielectric core and a dielectric interlayer is proposed, and its use for molecular sensing is investigated. First, an analytical model for the surface plasmon modes supported by this graphene geometry is presented and verified by finite element method simulations. Furthermore, we demonstrate a large tunability of the modes behavior by varying the Fermi level of the graphene, the coupling distance between the two sheets and the radius of the cylinder. Finally, a molecular sensing scheme based on the CGPW is proposed. Broadband spectroscopy of ethanol and toluene thin layers is realized by recording the changes in spectral intensity of the propagating mode. Due to the broadband localization capability of graphene plasmon mode which leads to a strong light-matter interaction in the midinfrared and terahertz regime, the proposed sensing scheme may provide an effective way for detecting nanometric-size molecules. (C) 2015 Optical Society of America