Detection Efficiency and Bandwidth Optimized Electro-Optic Sampling of Mid-Infrared Waves

This thesis investigates the detection efficiency of field-resolved measurements of ultrashort mid-infrared waves via electro-optic sampling for the first time. Employing high-power gate pulses and phase-matched upconversion in thick nonlinear crystals, unprecedented efficiencies are achieved for octave-spanning fields in this wavelength range. In combination with state-of-the art, high-power, ultrashort mid-infrared sources, this allows to demonstrate a new regime of linear detection dynamic range for field strengths from mV/cm to MV/cm-levels. These results crucially contribute to the development of field-resolved spectrometers for early disease detection, as fundamental vibrational modes of (bio-)molecules lie in the investigated spectral range.

The results are discussed and compared with previous sensitivity records for electric-field measurements and reference is made to related implementations of the described characterization technique. Including a detailed theoreticaldescription and simulation results, the work elucidates crucial scaling laws, characteristics and limitations. The thesis will thus serve as an educational introduction to the topic of field-resolved measurements using electro-optic sampling, giving detailed instructions on simulations and experimental implementations. At the same time, it showcases the state-of-the-art in terms of detection sensitivity for characterizing mid-infrared waves.

Auteur

Christina Hofer was born in Linz, Austria in 1993. She studied Physics at the University of Innsbruck, Austria and received her Bachelor s degree in 2014. Christina then moved to Munich to continue with a Master in Condensed Matter Physics at the Technical University Munich. After her Master s thesis at the Max Planck Institute of Quantum Optics and LMU Munich, Christina stayed at the institute for her PhD research from 2016 to 2021. She defended her thesis with greatest distinction, having become an expert in ultrafast laser science and nonlinear optics. Since then, Christina has been working as a Senior Laser Scientist at the Center for Molecular Fingerprinting and LMU Munich, developing field-resolved spectrometers for biomedical applications.