Transition from linear- to nonlinear-focusing regime in filamentation

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of...

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Bibliographic Details
Published in:Scientific reports 2014-12, Vol.4 (1), p.7217-7217, Article 7217
Main Authors: Lim, Khan, Durand, Magali, Baudelet, Matthieu, Richardson, Martin
Format: Article
Language:English
Subjects:
639/624/400/1119
639/624/400/385
639/624/400/584
639/766/1960/1135
Filamentation
Filaments
Gases
Humanities and Social Sciences
Lasers
multidisciplinary
Nonlinear systems
Optics
Science
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Summary:Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters and our analysis agrees well with a wide range of parameters found in published literature.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep07217