Self-compression by femtosecond pulse filamentation: experiments versus numerical simulations.
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.
Skupin
Stefan
S
Département de Physique Théorique et Appliquée, CEA-DAM/Ile de France, B.P. 12, 91680 Bruyères-le-Châtel, France. stefan.skupin@cea.fr
Stibenz
Gero
G
Bergé
Luc
L
Lederer
Falk
F
Sokollik
Thomas
T
Schnürer
Matthias
M
Zhavoronkov
Nickolai
N
Steinmeyer
Günter
G