ISBN 978-3-8439-4198-3

978-3-8439-4198-3, Reihe Physik

Michael Kolano
Design and characterization of a single-laser polarization-controlled optical sampling system

130 Seiten, Dissertation Technische Universität Kaiserslautern (2019), Softcover, A5

Zusammenfassung / Abstract

Pump-probe measurements enable time-resolved characterization of physical systems on a time scale not accessible for conventional electronic measurement equipment. Whether it is the observation of the actual motion of atoms in a chemical reaction or the transient dynamics of charge carriers in semiconducting materials: the general pump-probe approach has proven extremely useful for studying a vast variety of physical phenomena.

Essential for this type of measurement is the generation of two optical pulses with an adjustable temporal separation, which are then used to excite and probe the reaction of a sample under investigation. The obtainable temporal resolution of such a system is determined by the duration and the timing precision between the optical pulses.

With the advent of mode-locked lasers, pump-probe measurement systems steadily improved in terms of their size, performance and costs. One prominent application, which particularly benefits from the steady evolution in this field, is terahertz time-domain spectroscopy. Over the past years, terahertz technology is steadily growing in importance for scientific and industry-related applications.

Traditionally, a terahertz time-domain spectroscopy system requires either one mode-locked laser with an external delay line or two mode-locked lasers with controllable repetition rates. Both implementations have their advantages and disadvantages in terms of the obtainable performance and the related costs. This thesis presents the design, implementation and investigation of a novel approach, which combines the benefits of current single-laser and dual-laser systems into one solution.

The fundamental idea is the utilization of the polarization-maintaining capability of optical fibers and components used in mode-locked fiber lasers to enable the laser to emit two pulse trains with orthogonal polarization. Based on the underlying principle, this approach is called single-laser polarization-controlled optical sampling, or SLAPCOPS.