High-field multi-terahertz source

• Subject Area: Condensed Matter Physics
• Term: Funded in 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 581331689

The proposed laser system is designed to generate high-intensity, phase-locked light pulses in the mid-infrared range (central frequency: 25–60 THz; pulse energy: > 5 µJ) with a duration of a few oscillation cycles of the carrier field, as well as perfectly synchronized near-infrared scanning pulses (duration: <= 10 fs). In addition, the laser system will be used to generate single-cycle pulses in the THz spectral range by tilted-pulse front optical rectification. The MIR field transients will be used to drive strong field dynamics such as high harmonic generation (HHG) and high-order sideband generation (HSG) in solids. The spectral and temporal structure of the emitted electromagnetic radiation provides a direct picture of the subcycle dynamics of coherently accelerated charge carriers in modern quantum materials – important insights for the development of future electronics at optical clock rates. In particular, the focus is on strong-field phenomena in chiral Weyl semimetals, whose non-trivial topology and Berry phase should be reflected in the polarization state of the emitted high harmonics. Many-body correlations, which drive phase transitions in charge density waves or excitonic insulator states, also manifest themselves in the subcycle dynamics of accelerated charge carriers. Attosecond chronoscopy of the recollision trajectories of lightwave-driven electron-hole pairs could therefore provide crucial insights into the underlying quantum correlations. The low-frequency THz spectral range is ideally suited for driving magnons resonantly into a strongly nonlinear regime. Field-resolved two-dimensional spectroscopy aims to reveal the coupling of magnetic dynamics to other low-frequency elementary excitations in order to open up new possibilities for ultrafast and minimally dissipative switching of the spin order. The proposed laser system thus forms the basis for a series of successful third-party funded collaborative projects, ranging from Collaborative Research Center 1277 and Research Training Group 2905 to Cluster of Excellence 3112 and the ERC Synergy Grant project “Orbital Cinema.”

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Hochfeld-Multi-Terahertzquelle
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Universität Regensburg
• Leader: Professor Dr. Rupert Huber