Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 10: Ultrakurze Pulse: Erzeugung I
Q 10.5: Talk
Monday, March 2, 2009, 15:00–15:15, VMP 8 R206
Quasi-hydrodynamic spatio-temporal shaping in filamentary propagation of femtosecond pulses — •Carsten Bree1,4, Ayhan Demircan1, Stefan Skupin2, Luc Berge3, and Günter Steinmeyer4 — 1Weierstraß-Institut für Angewandte Analysis und Stochastik — 2Max-Planck-Institut für Physik komplexer Systeme — 3CEA-DAM, DIF, Arpajon, France — 4Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie
Filament self-compression is a remarkably simple new way for generating intense laser pulses with sub-10 fs pulse duration. Despite the experimental simplicity, the physical situation in femtosecond filaments is quite involved. In fact, the filamentary dynamics is governed by a complex interplay of about ten linear and nonlinear optical effects. We will show, however, that the formation of short pulses in the filamentary channel can already be well understood in a reduced model that isolates three major mechanisms. In particular, this model implies vanishing flow of energy between adjacent temporal slices of the pulse. In this quasi-hydrodynamic scenario, a pronounced self-induced pinching of the photon density is observed, leading to the characteristic spatio-temporal inhomogeneity of filamentary pulses. We will show, both by analytical arguments and numerical simulations that it is this spatial concentration of energy that gives rise to the experimentally observed self-compression. In addition, we show that the experimentally observed asymmetric temporal shape of self-compressed pulses, consisting of a small leading subpulse followed by an intense trailing pulse, can be understood within the framework of our analytical model.