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978-3-8439-0707-1, Reihe Physik
Rolled-Up Metamaterials Containing Active Semiconductor Quantum Structures
104 Seiten, Dissertation Universität Hamburg (2012), Softcover, A5
In this thesis the optical properties of rolled-up metamaterials are studied experimentally and theoretically. Based on the self-rolling concept of strained metal/semiconductor layers, rolled-up microtubes are fabricated. Their walls represent three-dimensional metamaterials consisting of alternating layers of metal and semiconductor.
In the first part of this thesis I present passive metamaterials consisting of several alternating layers of Ag and (In)GaAs. The optical properties of the rolled-up metamaterials are studied by reflection, transmission, and near-field transmission measurements. From transmission and reflection measurements we can determine the effective permittivities of the rolled-up metamaterials. Their transmission can be maximized utilizing Fabry-Pérot resonances in the total thickness of the material. Finite difference time domain simulations furthermore demonstrate that rolled-up metamaterials can act as broadband hyperlenses in a wide range of the visible spectrum.
In the next part the passive (In)GaAs layers are replaced by (AlIn)GaAs heterostructures containing optically active quantum wells. I illustrate that the self-rolling concept allows us to achieve three-dimensional metamaterials where layers of Ag are incorporated between active semiconductor quantum structures. Transmission measurements on these active metamaterials are performed while the embedded quantum well is excited optically with a pump laser. The measurements demonstrate that the transmission of the metamaterial can be enhanced under both continuous wave and pulsed excitation of the embedded quantum well.
In the last part of this thesis I present rolled-up active metamaterials containing an optically active semiconductor quantum structure and a metallic nanostructure. For that purpose a grating is integrated into the planar Ag and (AlIn)GaAs layers and the system is rolled up into an active grating metamaterial. Simulations predict that the optically active quantum well couples to surface plasmon polaritons provided by the metal grating. Indeed, the experimental transmission measurements on rolled-up active grating metamaterials show a coupling between the quantum well and the surface plasmon polariton resulting in an effective Fano resonance.