​In our research group, time-resolved Thz spectroscopy is the central method. THz radiation is long-wave infrared radiation that can penetrate many materials, e.g. semiconductors. A part of the THz radiation is absorbed by free charge carriers, for example.

The short THz pulses allow us to study the changes of a sample after optical excitation with high temporal resolution (~1ps). Among other things, we can observe how fast electrons release their energy to their surroundings. This depends strongly on the material and is often in the picosecond range (0.000000000001s). The results of these experiments allow us to draw conclusions about the interaction between the excited electrons and their environment.

On the one hand, this knowledge is important for the basic understanding of the processes in solids, but on the other hand it is also directly related to applications such as fast detectors for infrared radiation.

Especially so-called 2D materials, i.e. materials made of atomically thin layers such as graphene or plasmonic graphene structures, are the focus of our research. Ultra-short pulse lasers in the near-infrared range serve as radiation sources to excite the samples and generate the short THz pulses.