Metamaterial claddings for homotopic control of waveguide modes

In this paper, we explore this property in a new context: to design metamaterial blueprints for waveguide claddings. By using the proposed metamaterial claddings, better mode uniformity/confinement can be obtained with a precise control of the corresponding frequency waveguide cutoffs. In contrast to traditional (dielectric) loading of waveguides, the proposed metamaterial cladding does not produce hybrid modes. Instead, each resulting waveguide mode is homotopic to a canonical (hollow waveguide) mode, i.e., the former can be obtained from a continuous deformation of the latter. Physically, this means that inside the cladding, the mode is identical to the mode that would exist in a hollow waveguide of a different radius. For simplicity, we illustrate the design for PEC cylindrical waveguides, but the same basic idea applies to other types of PEC waveguides.