Phase-matched high order harmonic generation and applications

This dissertation presents an experimental study of High Harmonic Generation (HHG) using ultrafast laser pulses to produce radiation in the extreme ultraviolet. Two novel schemes which provided an additional phase for the fundamental and harmonic fields were used to enhance the quality of the HHG source including the conversion efficiency and the coherence. The interplay between the single-atom response and the macroscopic response, especially the role of macroscopic propagation effects on the HHG process, were investigated. The HHG source was applied to study rotational coherence dynamics of molecules and to implement coherent diffractive imaging in the extreme ultraviolet region.