title: Rainbow and blueshift effect of a dispersive spherical invisibility cloak impinged on by a nonmonochromatic plane wave.
abstract: We demonstrate some interesting phenomena associated with a nonmonochromatic plane wave passing through a spherical invisibility cloak whose radial permittivity and permeability are of Drude and Lorentz types. We observe that the frequency center of a quasimonochromatic incident wave will suffer a blueshift in the forward scattering direction. Different frequency components have different depths of penetration, causing a rainbowlike effect within the cloak. The concept of group velocity at the inner boundary of the cloak needs to be revisited. Extremely low scattering can still be achieved within a narrow band.
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. bzhang@mit.edu
authors.forename: Baile
authors.initials: B
authors.lastname: Zhang
authors.forename: Bae-Ian
authors.initials: BI
authors.lastname: Wu
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Chen
authors.forename: Jin Au
authors.initials: JA
authors.lastname: Kong