The Effects of Beam Stabilization on Mode Coupling in a Hollow Cylindrical Waveguide

High Harmonic Generation is a non-linear process that enables the tabletop production of coherent laser-like beams in the extreme ultraviolet and soft x-ray regions of the electromagnetic spectrum. In order to achieve significant high harmonic flux, the generated high harmonics must be phase matched. We achieve this by coupling the incident driving laser into a hollow cylindrical waveguide. The power coupling efficiency of this waveguide has an important dependence on spatial beam stability. This thesis discusses the power coupling efficiency of the incident beam into the waveguide with respect to beam position and angle at the entrance of the waveguide. It also presents an active beam stabilization technique which stabilizes both the angle and position of the beam. The performance of this beam stabilization is then be correlated to an increase in the stability of power coupling efficiency with the waveguide. Acknowledgments The author would like to thank the following: Dr. Daniel Adams and Matthew Seaberg as mentors whose guidance and hard work contributed to this thesis. Dr. Henry Kapteyn and Dr. Margaret Murnane for the opportunity to learn and grow as a member of the Kapteyn-Murnane Group. Dennis Gardner, Elisabeth Shanblatt, and Bosheng Zhang for their counsel on the imaging team. Dr. Patrik Grychtol for his aid in the laboratory. Everyone in the Kapteyn-Murnane Group!