Our group is interested in optical phonons in polar dielectric crystals and their heterostructures.
We use various linear and nonlinear mid-infrared to THz spectroscopy techniques, employing the
Infrared Free Electron Laser (IR-FEL) at the FHI
as an intense and tunable light source.
Using this unique laser, we study phase transitions in complex materials,
for instance correlated oxides, by means of the nonlinear-optical response enhanced at optical phonon resonances.
Additionally, we develop new platforms for infrared-to-THz nanophotonics based on surface phonon polaritons,
supported in sub-diffractional nanostructures and excited via prism coupling.
We also currently develop an experimental end station for FEL-based surface-specific vibrational
sum-frequency generation which will, for instance, allow us to study transient species in surface chemistry.