Asymptotic pulse shapes in filamentary propagation of intense femtosecond pulses (original) (raw)
Related papers
Asymptotic pulse shapes and pulse self-compression in femtosecond filaments
Ultrafast Phenomena XVI, 2009
The balance of Kerr-type and plasma-mediated self-amplitude modulations can give rise to self-stabilizing asymptotic pulse shapes in filament propagation. These soliton-like solutions resemble experimental data and constitute the major mechanism for self-compression in femtosecond filaments.
Cascaded self-compression of femtosecond pulses in filaments
2010
Highly nonlinear wave propagation scenarios hold the potential to serve for energy concentration or pulse duration reduction of the input wave form, provided that a small range of input parameters is maintained. Exploitation of this mechanism for pulse compression is ultimately limited by parameter fluctuations of the input wave. With high compression ratios, it becomes increasingly difficult to maintain control of the waveforms. Here, we suggest an alternative approach to the control of waveforms in a highly nonlinear system. Cascading pulse self-compression cycles at reduced nonlinearity limit the increase of input parameter sensitivity while still enabling an enhanced compression effect. This cascaded method is illustrated by experiments and by numerical simulations of the nonlinear Schrödinger equation, simulating the propagation of short optical pulses in a self-generated plasma.
Self-compression by femtosecond pulse filamentation: Experiments versus numerical simulations
2006
We analyze pulse self-compression in femtosecond filaments, both experimentally and numerically. We experimentally demonstrate the compression of 45 fs pulses down to a duration of 7.4 fs at millijoule pulse energies. This sixfold compression in a self-generated filament does not require any means for dispersion compensation and is highly efficient. We compare our results to numerical simulations, providing a complete propagation model that accounts for full dispersion, pressure variations, Kerr nonlinearity and plasma generation in multiphoton and tunnel regimes. The equations are numerically integrated and allow for a quantitative comparison with the experiment. Our experiments and numerical simulations reveal a characteristic spectrotemporal structure of the self-compressed pulses, consisting of a compressible blue wing and an incompressible red pedestal. We explain the underlying mechanism that leads to this structure and examine the scalability of filament self-compression with respect to pulse energy and gas pressure.
Dynamics of femtosecond filamentation from saturation of self-focusing laser pulses
Physical Review A, 2003
We study the effect of Two-Photon Absorption (TPA) nonlinear losses on Gaussian pulses, with power that exceeds the critical power for self-focusing, propagating in bulk kerr media. Experiments performed in fused silica and silicon highlight a spontaneous reshaping of the input pulse into a pulsed Bessel beam. A filament is formed in which sub-diffractive propagation is sustained by the Bessel-nature of the pulse.
Self-pinching of pulsed laser beams during filamentary propagation
2009
Competing nonlinear optical effects that act on femtosecond laser pulses propagating in a self-generated light filament may give rise to a pronounced radial beam deformation, similar to the z-pinch contraction of pulsed high-current discharges. This self-generated spatial beam contraction is accompanied by a pulse break-up that can be beneficially exploited for on-axis temporal compression of the pulse. The pinching mechanism therefore explains the recently observed self-compression and the complicated spatio-temporal shapes typical for filament propagation experiments.
2009
This chapter concerns with the experimental observations and theoretical investigations on the propagation of intense femtosecond pulses in water and fused silica. It emphasizes spontaneous transformation of a beam into a conical (Bessel-like) wave during the filamentary propagation in media with nonlinear losses. This transformation constitutes an interpretation of the energy reservoir surrounding the high intensity central core of the filament. The adopted model is shown as being able to explain related phenomena such as the formation of multiple filaments and that of X-waves, observed experimentally in both water and fused silica.
Self-compression of high-intensity femtosecond laser pulses in a low-dispersion regime
Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
Self-compression of high-intensity femtosecond pulses has been observed in a number of atomic and molecular gases and solid bulk material. The evolution of the femtosecond pulse parameters during the self-compression has been studied under a variety of experimental conditions. Generation of spatiotemporal solitons has been achieved by the combined action of self-compression and self-focusing.
Plasma induced pulse breaking in filamentary self compression
2010
A plasma induced temporal break up in filamentary propagation has recently been identified as one of the key events in the temporal self compression of femtosecond laser pulses. An analysis of the Non linear Schrödinger Equation coupled to a noninstantaneous plasma response yields a set of stationary states. This analysis clearly indicates that the emergence of double hump, characteristically asymmetric temporal on axis intensity profiles in regimes where plasma defocusing saturates the optical collapse caused by Kerr self focusing is an inherent property of the underlying dynamical model.