Rolled-up metamaterials

• Applicant: Privatdozent Dr. Tobias Kipp, since 8/2013
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 232331921

In this project we want to produce and investigate tailor-made three-dimensional optical metamaterials with built-in quantum emitters utilizing self-rolling strained metal-semiconductor layers. The production of three-dimensional metamaterials for optical frequencies requires three-dimensional nanostructuring and, therefore, is one of the current challenges in metamaterial research. To produce our metamaterials, we first grow strained InAlGaAs heterostructures using molecular-beam epitaxy. Atop these strained semiconductor layers we prepare metallic layers. The resulting metal-semiconductor system can be detached from the substrate by selectively etching the underlying AlAs sacrificial layer. Upon release from the substrate, the layered system, driven by strain minimization, rolls up into a micro-roll with several rotations. The walls of the resulting micro-roll are metamaterials consisting of metal-semiconductor multilayers. The metallic component of these metamaterials can be nanostructured before rolling up, and the semiconductor component can be functionalized with optically active quantum structures. We have proposed and demonstrated that this concept can be used to realize anisotropic metamaterials possessing tunable optical parameters and the potential for sub-wavelength imaging at visible frequencies. By embedding quantum wells into the semiconductor component, we were also able to optically activate the rolled-up metamaterials and show that their transmission can be controlled via optical pumping of the quantum well. Here, we want to continue this pioneering work and utilize the unique ability to stack mono crystalline semiconductor heterostructures and metallic nanostructures. This will allow us to investigate and tune the coupling between the excitons of the quantum emitters embedded within the semiconductor and the plasmons of metallic nanostructures. Furthermore, we want to prove and investigate the enhanced spontaneous emission of quantum emitters in our rolled-up anisotropic metamaterials. The enhanced spontaneous emission in anisotropic metamaterials has been discussed as the broad-band Purcell effect in recent literature. In addition, we want to experimentally prove broad band, sub-wavelength imaging at visible frequencies in our rolled-up metamaterials. For this project, we will combine the excellent infrastructure at the Center for Microstructure Research and the Institute of Applied Physics in Hamburg, with the expertise built up in our group for the production of rolled-up metamaterials and their investigation with optical near- and far-field methods.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Stefan Mendach, until 7/2013