Femtosecond laser pulse-train induced breakdown in fused silica: The role of seed electrons

Kaihu Zhang, Lan Jiang, Xin Li, Xuesong Shi, Dong Yu, Liangti Qu, Yongfeng Lu

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Femtosecond laser pulse-train induced breakdown in fused silica is investigated theoretically, with a focus on the role of ultrafast seed electrons during the pulse-train excitation. Material breakdown threshold is investigated by a model, which consists of both the excitation model and an improved optical model by including the optical absorption of self-trapped excitons (STEs). It is found that the evolution of a single train induced breakdown threshold is governed by the interplay of three competing sources of seed electrons initiating an electronic avalanche: residual conduction-band electrons left by the previous pulse, photoionization of atoms in dense media and photoionization of STEs by subsequent pulses. The third source provides a key to the understanding of some potential and existing problems involved, and leads to many pulse-separation independent phenomena (e.g. surface damage/ablation size) for pulse-train processing when it becomes dominant, and can contribute to the repeatable processing. For a single train of two or several femtosecond pulses, the third source can become dominant and sustained at large pulse-separations only when the first-pulse energy is over a critical value, ∼65-75% of the single-pulse breakdown threshold. Our calculations are in agreement with the experimental data.

Original languageEnglish (US)
Article number435105
JournalJournal of Physics D: Applied Physics
Volume47
Issue number43
DOIs
StatePublished - Oct 29 2014

Fingerprint

Fused silica
Ultrashort pulses
Seed
seeds
Photoionization
breakdown
silicon dioxide
Excitons
Electrons
pulses
Surface phenomena
lasers
electrons
Processing
Ablation
Conduction bands
Light absorption
Atoms
thresholds
photoionization

Keywords

  • laser materials processing
  • laser-induced breakdown
  • pulse train
  • seed electrons

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

Cite this

Femtosecond laser pulse-train induced breakdown in fused silica : The role of seed electrons. / Zhang, Kaihu; Jiang, Lan; Li, Xin; Shi, Xuesong; Yu, Dong; Qu, Liangti; Lu, Yongfeng.

In: Journal of Physics D: Applied Physics, Vol. 47, No. 43, 435105, 29.10.2014.

Research output: Contribution to journalArticle

Zhang, Kaihu ; Jiang, Lan ; Li, Xin ; Shi, Xuesong ; Yu, Dong ; Qu, Liangti ; Lu, Yongfeng. / Femtosecond laser pulse-train induced breakdown in fused silica : The role of seed electrons. In: Journal of Physics D: Applied Physics. 2014 ; Vol. 47, No. 43.
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