Colloidal energy transfer systems for spaser based nanolasing

• Applicant: Professor Dr. Matthias Karg
• Subject Area: Experimental and Theoretical Physics of Polymers ; Preparatory and Physical Chemistry of Polymers
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244259874

The proposed project aims at the development of colloidal energy transfer systems capable of gener-ating coherent photons in a well-defined wavelength regime, which is a rapidly evolving field of re-search. This research project provides important contributions to the preparation, characterization and theoretical understanding of nanoscaled optical components generating coherent photons for possible applications in sensing, sub-diffraction limit imaging, metamaterials and all-optical computing. For this purpose, we will use the spaser effect (Surface Plasmon Amplification by Stimulated Emission of Radiation) and employ plasmonic nanostructures to support and concentrate strong optical-frequency fields. In analogy to a classical laser, such a spaser requires a pump, a resonator and a gain medium. A major challenge in the realization of spaser based nanolasers is the gain efficiency, since the amplification by gain has to compensate optical losses to reach the critical threshold needed for lasing. We plan to increase the gain efficiency by using low optical loss plasmonic nanostructures and bright, photostable fluorophores to provide sufficient amplification. Most importantly we will analyze the energy transfer behavior systematically to determine the ideal fluorophore loading density and distance as well as fluorophore type. The strong research activity with respect to the synthesis and functionalization of plasmonic nanomaterials in the last years makes it now possible to experimentally realize energy transfer colloids which allow for spaser action. Furthermore, sophisticated spectroscopy tools for ensemble and single particle measurements are now available and will allow the actual identification of spaser performance. The present project combines elements of colloid and polymer chemistry, physics and theoretical simulation. Consequently, the proposed project in the framework of the Emmy Noether programme fits well into the research profile “Macromolecular and Colloid Research” at the University of Bayreuth and benefits from the strong scientific environment. The University of Bayreuth represents an excellent research platform, where junior scientists are systematically supported and find ideal working conditions. Excellent laboratories dedicated to synthesis of nanostructured materials can be found enabling synthesis of complex inorganic, organic and composite structures. In addition, a broad variety of instruments, important for characterization and processing of colloids, is available. The proposed project fits perfectly into the school of chemistry with the departments Physical Chemistry I (Prof. S. Förster), Physical Chemistry II (Prof. A. Fery) and the department Experimental Physics IV (Prof. J. Köhler). Institutions with a special research focus important for the present project such as the „Bayreuther Zentrum für Kolloide und Grenzflächen“ (BZKG) and the „Bayreuther Institut für Makromolekülforschung“ (BIMF) are accessible. Furthermore, the proposer’s research interests fit perfectly into the theme of the „Sonderforschungsbereich 840” (SFB 840).

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: Fluorescence Spectrometer
• Instrumentation Group: 1850 Spektralfluorometer, Lumineszenz-Spektrometer (außer Filterfluorometer