title: Deep nonlinear ablation of silicon with a quasi-continuous wave fiber laser at 1070 nm.
abstract: We achieve high aspect-ratio laser ablation of silicon with a strong nonlinear dependence on pulse duration while using a power density 10(6) times less than the threshold for typical multiphoton-mediated ablation. This is especially counter-intuitive as silicon is nominally transparent to the modulated continuous wave Yb:fiber laser used in the experiments. We perform time-domain finite-element simulations of thermal dynamics to investigate thermo-optical coupling and link the observed machining to an intensity-thresholded runaway thermo-optically nonlinear process. This effect, cascaded absorption, is qualitatively different from ablation observed using nanosecond-duration pulses and is general enough to potentially facilitate high-quality, high aspect-ratio, and economical processing of many materials.
authors.affiliation: Department of Physics, Queen’s University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Karen X Z
authors.initials: KX
authors.lastname: Yu
authors.forename: Logan G
authors.initials: LG
authors.lastname: Wright
authors.forename: Paul J L
authors.initials: PJ
authors.lastname: Webster
authors.forename: James M
authors.initials: JM
authors.lastname: Fraser