Date of Award

Spring 1-1-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

Margaret M. Murnane

Second Advisor

Henry C. Kapteyn

Third Advisor

Charles Durfee

Fourth Advisor

Sterling Backus

Fifth Advisor

Daniel Adams

Abstract

High-harmonic generation driven by two-color counter-rotating circularly polarized laser fields was recently demonstrated experimentally as a breakthrough source of bright, coherent, circularly polarized beams in the extreme ultraviolet and soft-x-ray regions. However, the conditions for optimizing the single-atom yield are significantly more complex than for linearly polarized driving lasers and are not fully understood. In this thesis, I present a comprehensive study of strong-field ionization–the complementary process to high-harmonic generation–driven by two-color circularly polarized fields. First, I describe a new experimental method that allows for the reconstruction of three-dimensional photoelectron angular distributions generated with two-color circularly polarized laser fields. Second, I present the first measurements of electron-ion rescattering in these fields, showing that the process can be systematically controlled by changing the parameters of the driving lasers. Finally, I present the first observation of nonsequential double ionization in two-color circularly polarized laser fields, showing how to optimize the yield of electrons that return to the parent ion at high energies. These findings help build an understanding of the single-atom physics behind high-harmonic generation. Additionally, since electrons ionized in two-color circularly polarized laser fields can be driven in two-dimensional trajectories before retuning to the parent ion, these findings will help inform the next-generation of experiments studying molecular dynamics on the ultrafast time scale.

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