Nanooptics
In the group of Johannes Boneberg the interaction of light with nanostructures as well as the application of light for the formation of nanostructures is studied in the following project areas:
Control of Magnetic Domains and Domain Walls by Thermal Gradients
Influence of laser light onto the electronic transport properties of atomic-sized contacts
Pulsed Laser Interference Lithography
Upon illumination of a surface or a thin film with an interference pattern of a pulsed laser a permanent structure might be induced. Although this process can be observed on a variety of surfaces the physical mechanisms behind are not well understood. We study therefore the ongoing processes on different surfaces by time-resolved methods as well as by characterization of the surface by scanning electron microscopy and atomic force microscopy. As the technique allows the periodic structuring of surfaces on sizes of several mm2 with periods ranging from 100 micron down to 150nm with a single laser pulse, it is a very flexible and fast approach for surface structuring. There-fore we study possible applications of this method as well.
Optical Nearfields
An electromagnetic field which interacts with metallic materials might be modified in a way that locally confined fields exist in the surrounding of the metallic structure. We study such optical nearfields by an unconventional method: the enhanced field is used for local ablation of the silicon substrate below the metallic structure by a femtosecond laser pulse. The ablation region, which reflects the local field can then be imaged with an atomic force microscope (AFM).
Dewetting of metals
Thin metallic films are typically not stable on oxide surfaces. Thus upon increasing the temperature dewetting will start which finally leads to individual nanoparticles. We study such dewetting processes after a temperature increase induced by a nanosecond laser pulse.