SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 33: Poster II

HL 33.53: Poster

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

Electro-optic response function of thin Quartz for sampling of high-field THz pulses — •Maximilian Frenzel, Michael S. Spencer, and Sebastian F. Maehrlein — Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany

As high-field THz sources are currently getting more broadly employed, it becomes increasingly important to characterize intense single-cycle THz fields (> 1 MV/cm) in amplitude and phase without saturation or nonlinearities in the electro-optic detection. After previous attempts of spectrally neutral attenuation, z-cut α-Quartz has been recently found as a suitable electro-optic sampling (EOS) crystal. Nevertheless, its accurate response function, which allows the THz electric field to be exactly determined from the measured EOS signal, is still missing. Here, we employ intense THz fields (0.5 - 4 THz) generated via optical rectification in LiNbO₃ to measure EOS in Quartz of various thicknesses between 30 and 150 µm. We find that both EOS peak amplitude and signal shape are significantly thickness-dependent. By modeling the Quartz EOS detector response function, we find good agreement between parameter free theory and experiment, thus explaining the measured thickness dependence. Our work will therefore allow accurate measurement of intense THz electric fields wherever conventional EOS materials are facing saturation effects.