Carpet Cloaks Based On Metamaterials/Graphene

Based on Transformation Optics, it is possible to achieve perfect cloaking in reality. In order to circumvent the rigorous requirements imposed by freestanding cloaks (i.e., anisotropy, singularity and inhomogeneity), carpet cloaking, as an alternative strategy, has been raised and widely studied by researchers from all over the world. Carpet cloaks work on metallic bumps and can control the wave passing through them, making the bump invisible. Previous work includes carpet cloaking in microwave, terahertz, infrared and optical frequencies; major transformation functions include Quasi-Conformal Mapping and Linear Transformation; major experimental materials are novel metamaterials, while some adopt natural birefringent materials.The dissertation mainly introduces the principles and experimental demonstrations of electromagnetic invisibility technology (especially carpet cloaking), as well as the electromagnetic properties and applications of metamaterials and graphene. The first chapter discusses the background, significance and research status of cloaking, determining the research directions and objects. The second chapter shares the theories and experiments related to carpet cloaks. The third chapter introduces metamaterials thoroughly, in particular, the closed rings and layered structures; the optical properties of graphene and its applications in novel optical devices are presented as well. The fourth chapter designs a graphene based free-space carpet cloak in THz by exploiting graphene’s anisotropic plasma-like behavior and proposes a TE-polarized broadband carpet cloak by utilizing closed rings. The fifth chapter shares the author’s other work based on metamaterials and graphene, including cylindrical cloaking, bandwidth expanding technology, subwavelength imaging, and so on. The last chapter summarizes the author’s work during Master, and shares his outlook for carpet cloaks.