Propagation dynamics of femtosecond laser pulses in argon

Abstract

The propagation dynamics of intense femtosecond laser pulses in argon have been investigated theoretically and the results are compared with experimental data. It was found that in the initial stage the pulse propagates with the focal point moving ahead of the original one. The central beam of the trailing part experiences defocusing owing to ionization by the leading part and then regains self-focusing provided by power from the outer part. On propagating further, a quasistable balance is established between self-focusing and defocusing due to ionization-induced nonlinearity and diffraction, causing the beam to propagate in a self-guided mode. Furthermore, it was shown that the front of the split pulse decays faster, while the trailing edge experiences self-focusing and self-defocusing until a self-guided propagation mode is achieved. Multiple pulse splitting and shortening as a result of the dynamics near the focal point were also observed.

Femtosecond filamentation in transparent media

“…Once split, the remaining power in a subpulse may exceed P cr and lead to subsequent self-focusing and propagation in the form of a filament. Nurhuda et al (2002a) confirmed this scenario and demonstrated pulse splitting and pulse shortening from 200 to 35 fs (see the computed temporal profiles in Fig. 28).…”

“…Filamentation in low pressure argon was predicted to occur (Mlejnek et al, 1998b) and observed (Nurhuda et al, 2002a;Hauri et al, 2004). The features of filaments at low air pressure have been studied numerically by Couairon et al (2006b).…”

Nonlinear pulse propagation in a single- and a few-cycle regimes with Raman response

“…Based on this, they derived a nonlinear pulse evolution equation that represents a generalization of the well-known nonlinear Schroedinger equation. This model equation has been successfully used by several authors [13][14][15][16][17] in various studies including nonlinear propagation dynamics of an ultrashort pulse in a hollow waveguide [13], supercontinuum generation by filamentation of a few-cycle pulses [14], estimation of the critical power for self-focussing in bulk media and in hollow waveguides [15], 501…”

Systematic study of spatiotemporal dynamics of intense femtosecond laser pulses in BK-7 glass

“…We have classified the study into three different regimes depending on the mechanism that arrests collapse and the different spatio-temporal characteristics which are a consequence of the interplay between self-focusing and the arresting mechanisms. For intensities just above P cr , GVD combines with SPM to broaden [21] and split [28][29][30] the pulse temporally to prevent collapse and also the formation of appreciable plasma. The dynamics are governed entirely by GVD up to the threshold power for the formation of plasma P th (defined in eq.…”