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

✍ Scribed by Christina Hofer

• Publisher: Springer
• Year: 2022
• Tongue: English
• Leaves: 131
• Series: Springer Theses
• Category: Library

✦ Synopsis

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 theoretical description 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.

✦ Table of Contents

Supervisor’s Foreword
Abstract
Acknowledgements
Contents
Acronyms
1 Introduction and Motivation
References
2 Theoretical Background
2.1 Linear Optics
2.2 Perturbative Nonlinear Optics
2.3 Theoretical Description of EOS
2.3.1 Sum- and Difference-Frequency Generation
2.3.2 Pockels-Effect
2.3.3 Comparison to Time-Integrating MIR Characterization Techniques
2.4 Nonlinear Crystals and Phasematching
2.5 Noise in Balanced Detection
2.6 Techniques to Improve the EOS Dynamic Range and Sensitivity
References
3 Simulation Results for EOS
3.1 Wavelength-Dependent EOS Signal for Thick Detection Crystals
3.2 MIR Depletion and Amplification for Phasematching SFG or DFG
3.3 Temporal and Spectral Transfer Functions
3.4 Detection Bandwidths for Different Gate Pulse Wavelengths
3.5 Pre-chirping of 1550-nm Gate Pulses
References
4 Experimental Results
4.1 Optimization and Characterization of EOS with 1-m Gate Pulses
4.2 Dynamic Range and Background-Reduced Measurements
4.3 Bandwidth-Efficiency Trade-Off
4.4 Multiple Reflections from GaSe
4.5 Application of High-DR EOS: Waveform Stability Analysis
4.6 EOS with 1550-nm Gate Pulses
4.7 EOS with 2-m Gate Pulses
4.8 Optimized 2-m EOS: Reaching Percent-Level Detection Efficiency
4.9 Linearity of Large Depletion EOS Measurements
References
5 Conclusion and Outlook
References
Appendix A Data Archiving
Appendix B Setup of the 2-m EOS
Appendix C Curriculum Vitae