Femtosecond multiple filamentation of an optical vortex in the mid-IR wavelength range in fused silica and fluorides. (1st April 2022)

• Record Type: Journal Article
• Authors: Shlenov, S.A.; Kompanets, V.O.; Dergachev, A.A.; Kandidov, V.P.; Chekalin, S.V.; Soifer, F.I.
• Is Part Of: Quantum electronics. Volume 52:Number 4(2022)
• Page Start: 322
• Page End: 327
• Publication Date: 2022-04-01
• Subjects: femtosecond pulses -- optical vortex -- phase dislocation -- critical power -- multiple filamentation -- fused silica -- LiF crystal -- filament plasma channels; Quantum electronics -- Periodicals; 537.5
• DOI: 10.1070/QEL18028
• Languages: English
• ISSNs: 1063-7818

Abstract

Abstract: The results of experimental and theoretical study of the self-action of femtosecond optical vortices in the region of anomalous group velocity dispersion in fused silica and fluorides are presented. Multiple filamentation of an axially asymmetric annular beam with a phase dislocation of topological charge m = 1 at a wavelength of 1800 nm in a LiF crystal is investigated. It is found that for the experimentally recorded intensity profile of a vortex beam with two maxima on the diameter, the critical self-focusing power is approximately two times larger than the critical power of a unimodal Gaussian beam. In pulses with supercritical power in the vicinity of the intensity maxima, two coupled filaments, separated by a phase dislocation, are formed on the annular profile of the optical vortex, which prevents energy exchange during their formation. The length of vortex-beam plasma channels in a single pulse is found to be about 300 μm at a diameter of about 2 μm, which is close to the characteristics of plasma channels in a Gaussian beam.