Transient field-resolved reflectometry at 50-100 THz

Transient field-resolved spectroscopy enables studies of ultrafast dynamics in molecules, nanostructures, or solids with sub-cycle resolution, but previous work has so far concentrated on extracting the dielectric response at frequencies below 50 THz. Here, we implemented transient field-resolved reflectometry at 50-100 THz(3-6 mu m) with MHz repetition rate employing 800 nm few-cycle excitation pulses that provide sub-10 fs temporal resolution. The capabilities of the technique are demonstrated in studies of ultrafast photorefractive changes in semiconductors Ge and GaAs, where the high frequency range permits to explore the resonance-free Drude response. The extended frequency range in transient field-resolved spectroscopy can further enable studies with so far inaccessible transitions, including intramolecular vibrations in a large range of systems. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.

Automated summary

Transient field-resolved spectroscopy enables the study of ultrafast dynamics with sub-cycle resolution. Previous work focused on frequencies below 50 THz, but this study implemented transient field-resolved reflectometry at 50-100 THz. The technique was demonstrated in studies of ultrafast photorefractive changes in Ge and GaAs semiconductors, exploring the resonance-free Drude response. The extended frequency range in transient field-resolved spectroscopy allows for previously inaccessible transitions to be studied in a wide range of systems.