Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 99: Ultrafast Electron Dynamics IV
O 99.9: Vortrag
Freitag, 21. März 2025, 12:30–12:45, H11
Ultrafast imaging ellipsometry or interferometry - Which one is more suitable to measure the dielectric function of laser-excited materials? — •Markus Olbrich, Theo Pflug, Andy Engel, and Alexander Horn — Laserinstitut Hochschule Mittweida, Hochschule Mittweida, Technikumplatz 17, 09648 Mittweida, Germany
Changes of the dielectric function of materials due to excitation by ultrafast laser radiation are crucial for understanding fundamental processes such as absorption of electromagnetic radiation or the relaxation of the excited electrons resulting in changes in the density of state of the material. The transient dielectric function can either be measured by ultrafast ellipsometry or interferometry. This study evaluates the advantages and disadvantages of each method exemplarily for an excited thin gold film induced by ultrafast laser radiation (λ = 800 nm, τH = 40 fs) at fluences below and above the ablation threshold. The focus of the presentation is on characterizing the methodology including the experimental effort, the obtained signal-to-noise ratio, the data evaluation particularly in the limits of the applied optical model, as well as the physical interpretation of the measured data.
Keywords: Ultrafast Laser Radiation; Pump-Probe; Ulrafast Imaging Ellipsometry; Two-Temperature Model Hydrodynamics; Ultrafast Imaging Interferometry