Mathe im Beruf Detailseite

Speaker:
Prof Georg Herink - University of Bayreuth

Ultrafast waveforms at multi-Terahertz frequencies govern a broad range of elementary excitations in condensed matter –including the motion of conduction electrons, atomic vibrations and quasi-particle excitations. Critical field extensions are often spatially confined below sub-diffraction scales and underlie surface polaritons in layered 2D-materials, metamaterials and nanoscale devices.
In this lecture, I will introduce a fluorescence-based microscope to capture sub-cycle movies of evolving far-infrared electric near-fields. The approach employs the quantum-confined Stark-effect in semiconductor nanocrystals acting as ultrafast probes coated onto the sample. Based on far-field microscopy in the visible spectrum, we directly image momentary electric field distributions at super-resolution with bandwidths exceeding several THz. We also derive strategies to break the symmetric response of the Stark-effect to access the absolute polarity of the waveforms. Furthermore, I will discuss regimes of intense excitations and present the THz-driven transient enhancement of quantum dot luminescence –establishing single-cycle high-field THz biasing as an ultrafast probe to access carrier dynamics within nanostructures.