Extended laser filamentation in air generated by femtosecond annular Gaussian beams

Effects of delayed Kerr nonlinearity on the propagation of femtosecond annular Gaussian filaments in air

“…In this work, we still use our previously proposed model [32,33]. A femtosecond annular Gaussian beam at central wavelength λ 0 =800 nm with a larger diameter (denoted by the radius r 0 ) wavefront passes through an optical system, which is composed of a shallow axicon and a fused silica plano-concave lens.…”

“…In addition, the delayed Kerr nonlinearity not only strongly modifies the dynamics of propagation by distorting the pulse shape [27,28], but also dramatically changes the beam diameter, the beam timesplitting, the on-axis laser intensity and the electron density [29]. However, when the pulse duration is far from the characteristic time (τ κ =70 fs) of the molecular rotational respond in air, the delayed Kerr nonlinearity could be neglected in the propagation of optical filament in air [30][31][32][33]. At present, it remains unclear that the delayed Kerr nonlinearity depends on the different initial pulse lengths near the characteristic time.…”

“…In this paper, we have primarily analyzed the effects of the delayed Kerr nonlinearity on the optical filament produced by an annular Gaussian beam (the beam with zero center intensity). In our previous work [32], we proposed a new scheme that an annular Gaussian beam and a conventional Gaussian beam passed through an optical system, which was composed of an axicon and a plano-concave lens, and analyzed specifically the difference of the modulation effect of the concave lens and the nonlinear dynamics mechanism between the two types of laser beams. The results demonstrated that the combination of an axicon with a concave lens can increase the length of the ring-Gaussian filament remarkably comparing with Gaussian filament under the same initial condition.…”

Hollow Gaussian beam generation through nonlinear interaction of photons with orbital angular momentum

“…Like conventional DHBs such as optical vortices 1 , higher order Bessel 2 and Mathieu 3 beams, HGBs 4 5 also have doughnut intensity profile but do not carry any OAM. In addition to the vast applications ranging from atomic optics to plasma physics 6 7 8 9 10 11 12 13 14 15 , HGBs have also attracted a great deal of scientific interest in understanding its propagation and transformation dynamics 5 16 17 18 . Generation of HGBs have been realized using linear optical elements in different methods such as spatial filtering 19 , geometrical optics 20 , fibers 21 , spatial-light-modulator 16 , and Laguerre-Gaussian (LG) beam transformation 22 .…”

“…Generation of HGBs have been realized using linear optical elements in different methods such as spatial filtering 19 , geometrical optics 20 , fibers 21 , spatial-light-modulator 16 , and Laguerre-Gaussian (LG) beam transformation 22 . However, nonlinear generation processes enable HGBs to have a new wavelength across electromagnetic spectrum and also to have high output power and higher order in all timescales as required for most of the applications 6 7 8 9 10 11 12 13 14 15 .…”