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Gradient index metamaterial based on slot elements

: Paul, O.; Reinhard, B.; Krolla, B.; Beigang, R.; Rahm, M.


Applied Physics Letters 96 (2010), No.24, Paper 241110, 3 pp.
ISSN: 0003-6951
ISSN: 1077-3118
Journal Article
Fraunhofer IPM ()
gradient index optics; lenses; metamaterial; refractive index; terahertz wave

We present a gradient-index (GRIN) metamaterial based on an array of annular slots. The structure allows a large variation in the effective refractive index under normal-to-plane incidence and thus enables the construction of GRIN devices consisting of only a small number of functional layers. Using full-wave simulations, we demonstrate the annular slot concept by means of a three-unit-cell thin GRIN lens for the terahertz (THz) range. In the presented realizations, we achieved an index contrast of Δn = 1.5 resulting in a highly refractive flat lens which is suitable for focusing THz radiation to a spot size smaller than the wavelength.