Filamentation
Filamentation describes the ability of a very intense ultrashort laser pulse to remain focused over an extended distance (from several Rayleigh lengths to several kilometers).
Filaments arise from the nonlinear propagation of ultrashort, high-power laser pulses in transparent media. They result from a dynamic balance between Kerr-self-focusing and defocusing by negative higher-order Kerr effect (HOKE) and/or self-induced plasma, depending on the pulse duration and wavelength. The relative contributions of these defocusing processes is one of the most active research topic in the field of filamentation (See. e.g. P. Béjot et al. Phys. Rev. Lett. 104, 103903 (2010) and 106, 243902 (2011)) Our research now aims at identifying the physical processes behind the HOKE.
In parallel with the experimental work, we develop and maintain a propagation code based on the Unidirectional pulse propagation equation (UPPE) describing the filamentation of ultrashort pulses in radial symmetry.
Our research focuses on understanding similarities between laser filamentation and other nonlinear systems, including self-patterning (See Beguin et al. Scientific Reports, 9, 1499, 2019 - (link) and Mongin et al., Physical Review Letters, 118 133902, 2017 - (link)) or rogue waves (link) (see Kasparian et al., Optics express, 17, 12070-12075 (2009) - (link), Gomel et al., Physical Review Letters 126, 174501, 2021 - (link), Eeltink et al., Physical review, A 94, 033806 (2016) - (link)). We are also interested in characterizing the transition to filamentation in various conditions, characterizing the statistical distributions of intensity in order to better understand the filamentation onset as well as to develop better early warning of tipping transitions to long-tailed distributions.