Keywords

Ultrafast Optics; Attosecond Science; Optical Field Sampling; Few-Cycle Laser Pulses; Pump-Probe Spectroscopy; Field-Resolved Metrology

Abstract

Ultrashort pulses of light have opened new frontiers in both fundamental science and applied technology. The short duration and large bandwidth of these pulses has enabled time-resolved spectroscopy of atomic and molecular dynamics at their natural timescales, allowing direct observation of ultrafast processes in these systems which is essential to our fundamental understanding of material behavior. Alongside these optical developments, free-electron lasers (FELs) have advanced the generation of attosecond X-ray pulses. These state-of-the-art facilities allow scientist to probe even deeper into the atomic nature of matter. To access these dynamics, pump-probe experiments are run in which a short optical pulse excites a sample, and a delayed X-ray pulse probes its response. To achieve high temporal resolution in such experiments it is critical to measure precisely the delay between the pump and the probe pulse. While attosecond precision is more easily achieved in systems where the pump and the probe are derived from the same sources, large-scale FEL facilities—where X-ray and optical pulses originate from independent sources—typically have timing jitter on the order of hundreds of femtoseconds.

This dissertation presents a field sampling approach towards achieving attosecond resolution in optical pump, X-ray probe experiments. The approach is based on optical field sampling of few-cycle NIR pulses to track the instantaneous X-ray induced modification of high-Z targets allowing for sub-femtosecond time-tagging. To this end, results on the generation of ultrashort, broad-bandwidth near-infrared pulses using spectral broadening in both molecular and noble gas-filled hollow core fibers, and the development of an optical field sampling technique capable of resolving sub-cycle variations in the electric fields of those pulses using wide-bandgap photodiodes are presented. In addition, simulation results validating the methods ability to provide sub-femtosecond time-tagging are shown.

Completion Date

2025

Semester

Fall

Committee Chair

Michael Chini

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Format

PDF

Identifier

DP0029777

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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