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HL: Fachverband Halbleiterphysik

HL 33: Poster II

HL 33.55: Poster

Wednesday, March 29, 2023, 17:00–19:00, P1

MIR Time-Domain Ellipsometry via 2D Electrooptic Sampling — •Leona Nest, Michael Scott Spencer, Martin Wolf, and Sebastian Maehrlein — Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Faradayweg 4-6, 14195 Berlin, Germany

Terahertz time-domain spectroscopy (THz-TDS) has been established as a powerful tool in fundamental material science as it allows to measure conductivities, dielectric functions, and related phase transitions in e.g. semiconductors, topological insulators, and high-temperature super-conductors. Moreover, THz-TDS is well suited to investigate ultrafast, and thus non-equilibrium, quasi-particle dynamics in such solid- state systems. The time-resolved detection of the electric field provides direct access to complex-valued static and transient material properties. Here, we extend this technique to additionally measure the temporal evolution of the field's polarization for direct determination of complex tensorial material responses. Operating our time-domain ellipsometer in the mid-Infrared (MIR, 15-40 THz) enables anisotropic transmittivity or reflectivity studies in a spectral region where fundamental resonances such as phonons can be found. As a benchmark system, we extract the complex-valued dielectric tensor components of y-cut α-quartz in the vicinity of its anisotropic 21 THz and 24 THz phonon resonances. Good agreement with free-electron-laser-based studies shows that we developed a versatile table-top time-domain ellipsometer that will be used to also measure non-equilibrium tensorial properties in the near future.