Study Of Space Wave Manipulation Using Graphene Metasurfaces

Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms packed in a honeycomb crystal lattice.As a new two-dimensional material,graphene exhibits excellent electron mobility,optical transparency and mechanical strength.Graphene plasmonic resonance can change electromagnetic properties of incident waves.Hence,periodical patterned graphene structures can be used as meta-atoms of metasurfaces to manipulate properties of space waves.Moreover,electric conductivity of graphene and functionality of the graphene metasurface can be dynamically tuned by bias voltage.The space wave manipulation using graphene metasurfaces has been theoretically investigated in this dissertation.The main contents of the dissertation are as follows:1.Graphene and graphene plasmonic resonance are briefly introduced.Then,the research progresses of metasurfaces and graphene metasurfaces are reviewed.2.The electromagnetic characteristics of graphene are studied.Graphene surface conductivity and its reduced forms under different conditions are analyzed.Three different methods are introduced to tune graphene conductivity.The effective permittivity and surface impedance are derived to make accurate electromagnetic modeling of graphene.3.Graphene complementary metasurfaces to realize polarization-independent transparency windows are proposed.Parameter analysis and numerical fitting methods show the physics origin of transparency windows.The dynamical tune effect of transparency windows and slow-light effect at window frequency are also demonstrated.4.The wavefront manipulation of space wave using graphene metasurfaces is studied.The equation of two-dimensional anomalous reflection is derived based on Fermat's principle.Then,graphene metasurfaces are designed to realize two-dimensional anomalous reflection.Finally,combining the concepts of vortex wave and gradient metasurfaces,graphene metasurfaces to generate vortex waves with different modes are designed.