ORCID

0009-0001-2038-6460

Keywords

filamentation, laser ablation

Abstract

The high-power densities delivered to a target material by a laser allow for melting and vaporization to occur, a process called laser ablation. At higher intensities, plasma formation occurs and more complex material removal mechanisms take place. As laser power increases, nonlinear effects occur during propagation. One such effect, Kerr self-focusing, leads to beam collapse and ionization, resulting in a channel of plasma and region of high intensity light referred to as a laser filament. Filaments carry intensities on the order of 1013 W/cm2 to significant distances without the use of large-scale focusing optics. Laser filament ablation is limited due to the clamped energy carried by a filament, as excess energy leads to break up into multiple filaments within the pulse. This work expands upon initial efforts to overcome this limitation by temporally structuring pulses of femtosecond pulses into bursts with nanosecond-scale durations. Laboratory results show a significant increase in the ablation rate of such bursts compared to single filaments and nanosecond pulses of equal envelope energy. Additionally, a significant increase in energy coupling to the laser-produced surface shockwave is observed. Low pressure filament ablation was studied for the first time, and it was shown that single filaments produce ablation craters with increased volume at low pressure. Most laboratory filamentation experiments assist filament formation with the use of a weak lens. The effects of such focusing preconditions on filament structure and resultant changes in ablation are examined. Bursts of filaments formed without the use of focusing optics display notable change in ablation rate and crater shape. It has been shown that the cause of this difference in ablation rate between focusing regimes in burst mode arises from both a change in filament fluence and the number of pulses that are filamenting at any position during propagation.

Completion Date

2026

Semester

Spring

Committee Chair

Martin Richardson

Degree

Doctor of Philosophy (Ph.D.)

College

College of Optics and Photonics

Format

PDF

Document Type

Dissertation

Identifier

DP0053149

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