|Title||Active negative-index metamaterial powered by an electron beam|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||M. Shapiro, S. Trendafilov, Y. Urzhumov, A. Alù, R. Temkin, G. Shvets|
|Journal||Physical Review B|
An active negative index metamaterial (NIM) that derives its gain from an electron beam is introduced. The metamaterial consists of a stack of equidistant parallel metal plates perforated by a periodic array of holes shaped as complementary split-ring resonators (C-SRR). It is shown that this structure supports a negative-index transverse magnetic electromagnetic mode that can resonantly interact with a relativistic electron beam. Such a metamaterial can be used as a coherent radiation source, a particle accelerator, and as a component of various novel vacuum electronics devices that require backward waves and small group velocity. The subwavelength nature of the unit cells enables strong interaction with electron beams at the fundamental harmonic of the structure, making a step towards minituarization of vacuum electronics and table-top accelerators. An analytic homogenization theory of an active beam-powered NIM is developed, which includes magnetoelectric coupling (bianisotropy) of the C-SRR. The theory makes use of transmission-line characteristic impedances of a metamaterial waveguide. Dispersion relations of the relevant modes are also computed numerically using the finite element method.
|Short Title||Phys. Rev. B|