title: Chiral Swiss rolls show a negative refractive index.
abstract: Chiral Swiss rolls, consisting of a metal/dielectric laminate tape helically wound on an insulating mandrel, have been developed to form the basis of a highly chiral metamaterial. We have fabricated these elements using a custom-built machine, and have characterized them. We find that the permeability, permittivity, and chirality are all resonant in the region of 80 MHz. The chirality is so strong that it can be directly measured by observing the magnetic response to an applied electric field, and is larger than either the permeability or the permittivity. We have estimated the refractive indices from these data, and find both strong circular dichroism and a wide frequency range where the refractive index is negative.
authors.affiliation: Imaging Sciences Department, Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Ducane Road, London W12 0NN, UK. The Blackett Laboratory, Department of Physics, Imperial College London, South Kensington, London SW7 2AZ, UK.
authors.forename: M C K
authors.initials: MC
authors.lastname: Wiltshire
authors.forename: J B
authors.initials: JB
authors.lastname: Pendry
authors.forename: J V
authors.initials: JV
authors.lastname: Hajnal