Umeå universitets logga

Throughout the history of laser development, the generation of ultra-short pulses has always been one of the most active frontiers. The generation of visible light pulses that contain only a few optical cy-cles is therefore a major achievement of modern physics. Femtosec-ond laser pulses now find applications across science, medicine, industrial manufacturing, and telecommunications, impacting many aspects of modern life.

This thesis presents the generation, characterization, and application of few-cycle light pulses. It includes the development of the Light Wave Synthesizer 100, one of the pioneering systems for waveform-controlled ultrafast optics. Throughout my thesis, this system was up-graded to facilitate higher peak intensities, shorter pulses and carrier-envelope phase (CEP) stabilization. A key contribution of this thesis is the the development of a new compression chamber layout.

The broad spectra required for few-femtosecond pulses can give rise to spatio-spectral couplings. To characterize and control these effects, reliable measurement techniques are necessary. The sim-plified INSIGHT method is presented and evaluated against HASO multispectral, a commercially available device to whose development our research group, the RElativistic Attosecond physics Laboratory (REAL), contributed.

There are fundamental limits to how short a pulse of a given spectrum can be, commonly referred to as the Fourier transform limit. Different approaches are demonstrated how this limitation can be circumvented, supported by both simulations and experimental results.

Finally, one of the main applications of ultrashort pulses is the field of ultrafast spectroscopy. A central component of this work is the development of a degenerate pump-probe setup with excep-tional sub-5-fs time resolution. This experimental platform is applied to a strongly coupled exciton-cavity system to observe the ultrafast generation and decay of polaritons, as well as excitons in WS2, a semiconducting transition metal dichalcogenide.