Ultrafast spatially-inhomogeneous optical nonlinearities of metal nanostructures analyzed by ab-initio based Maxwell-Bloch equations

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Metallic and hybrid nanostructures allow one to control and design electromagnetic fields on ultrashort time and nanometer length scales. These fascinating possibilities arise due to an interplay between the elementary excitations of the involved materials and the light field. The light-matter interaction with nanostructures depends on their shape and in many cases, in particular, on the electronic structure of the involved surfaces and interfaces. For example, close to metal surfaces, edges, and corners fields are often strongly enhanced due to the presence of freely moving electrons. We plan to develop an approach that is capable of describing the linear and nonlinear optoelectronic properties of metal and hybrid nanostructures on a microscopic basis. The starting point will be computations of the electronic band structure and wave functions via ab-initio density functional theory. These results will be used to set up Bloch-type equations for the material dynamics which will be solved numerically self-consistently with Maxwell’s equations. Our realspace equation of motion approach provides a detailed microscopic description of ultrafast effects on the nano scale. The gained understanding will be used to analyze experiments and for the development of novel design concepts. Furthermore, our approach will be applied to coherent control techniques of the light-matter dynamics by, e.g., pulse shaping.