Abstract
The conditions for filamentation of femtosecond pulse laser radiation when focusing in air are studied experimentally and theoretically. A good agreement between experimental and calculated results is shown if neglecting the filament plasma. It is shown that the Kerr nonlinearity plays a fundamental role in the generation, existence, and cessation of a filament at a small numerical aperture (NA ≤ 2.15 × 10–3). The Kerr effect first leads to the beam self-focusing and generation of a filament, and at the final stage, to radiation defocusing and a sharp decrease in its axial intensity due to the beam wavefront distortions. In the case of aberration focusing, a spatial quasi-soliton is formed after a visible filament due to the balance between Kerr self-focusing and diffraction spreading. The quasi-soliton is a source of the directional white supercontinuum.
Original language | English |
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Pages (from-to) | 331-336 |
Number of pages | 6 |
Journal | Atmospheric and Oceanic Optics |
Volume | 30 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1 Jul 2017 |
Keywords
- filamentation
- focusing
- Kerr nonlinearity
- supercontinuum
ASJC Scopus subject areas
- Oceanography
- Atomic and Molecular Physics, and Optics
- Earth-Surface Processes
- Atmospheric Science