The aim of the project is the development of nanostructured materials in which the interaction of optical near-fields and disorder-induced fluctuations of local electromagnetic fields are optimally used to create novel photonic functionality. While nature uses disordered nanomaterials for butterfly colors, we humans have only recently learned to use metallic nanostructures for the detection of single molecules. Systematic investigations to optimize disorder with the aim of maximizing the coupling of local electromagnetic fields to suitable quantum emitters (laser dyes, J-aggregates, semiconductor quantum dots, ...) are almost completely lacking, although major advances in nanomaterials, optical spectroscopy and theoretical solid state physics have created the prerequisites. For this project, scientists from all three fields have joined forces to (i) maximize local electromagnetic field fluctuations by optimizing the disorder in specially selected quasi-two- and three-dimensional metallic and dielectric nanostructures and (ii) insert quantum emitters in such a way that their optical nonlinearity provides new photonic functionality. We expect this approach to yield inherently robust systems: If varying environmental parameters destroy the resonance of a given emitter-local electromagnetic mode pair, this will be compensated by another equivalent pair.
The project focuses on three classes of disordered systems: (i) dense fields of nano-needles of transparent oxide and nitride semiconductors, (ii) percolating metal films with pores and islands in the nanometer range, and (iii) nanoporous gold nanoparticles of two-phase alloys. These samples are coated or infiltrated with optically nonlinear materials.
Besides the design of possibly even economically relevant photonic materials, we expect that the project will lead to a deeper understanding of the light-matter interaction at the nanoscale, the physics of disorder-induced light and plasma localization and - more generally - of fluctuation dominated systems. We plan to measure the time structure of individual localized electromagnetic modes in Oldenburg in real time and to map their spatial structure with 20 nm resolution. The theoretical analysis is based on the expertise of the Ilmenau group in the fields of Anderson localization and exciton-plasmon coupling. Materials with tailor-made disorder are provided by Ilmenau materials scientists. Close interdisciplinary cooperation and continuous feedback between the scientists involved is essential for the creation of materials with tailor-made disorder and new or at least improved photonic functionality.
