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978-3-8439-1043-9, Reihe Physik
Investigation of Radial Metamaterials
216 Seiten, Dissertation Universität Hamburg (2013), Softcover, A5
In this thesis we investigated radial metamaterials analytically and with computer simulations. The results are presented in eight publications in peer-reviewed journals that are included in this thesis and can be divided into three topics:
(i) Rolled-up metamaterials: In previous works in our group it was demonstrated that self-rolling strained metal-semiconductor layers can be used to produce metamaterials based on metal-semiconductor microtubes. In publication 1 we investigate the use of the walls of metal-semiconductor microtubes as broadband hyperlenses and demonstrate that the hyperlensing ability is not limited to the effective plasma frequency of the structure, but occurs over a broad frequency range. Publication 2 investigates the creation of a magnetic response in arrays of metal-semiconductor microtubes. It is found that, if the structure dimensions are appropriately chosen, a negative effective permeability at terahertz frequencies can be achieved. We show in publication 3 that by drilling an array of nanoholes into the wall of a metal-semiconductor tube, a fishnet structure with a negative refractive index at near-infrared frequencies can be obtained. Our rolling-up technique allows the fabrication of stacked semiconductor quantum wells that are sandwiched between plasmonic nanostructures. In publication 4 we investigate the influence of surface plasmon polaritons on the quantum-well gain and find a fano-type coupling that can provide a strong transmission enhancement.
(ii) Hybrid plasmon-photon modes: Surface plasmon polaritons usually suffer from rather low quality factors, limiting their use in potential applications. In publication 5 and 6 we propose and demonstrate the application of hollow metal cylinders and metal-coated dielectric bottle resonators as microresonators for surface plasmons. We show that such resonators support hybrid high-quality-factor plasmon-photon modes with a plasmon-type field enhancement at the metal-air surface of the structure. The quality factors of these modes are up to 1000. The combination of high quality factors and plasmon-type field concentration at the resonators surface makes our structures particularly interesting for sensing applications.
(iii) Metal-dielectric transformation-optics devices: In publication 7 we show that a metamaterial consisting of metal particles that are embedded in a dielectric host material can be used to fabricate transformation-optics devices such as an invisibility cloak or an optical black hole at visible frequencies. We demonstrate in publication 8 that a straightforwardly realizable metal-rod device can act as an invisibility cloak in the visible regime.