Nonlinear Optics in Guided Geometries - Abstract
Skupin, Stefan
In self-generated filaments, femtosecond pulses experience strong spatial and temporal shaping effects. The dynamical balance between Kerr self-focusing and plasma-induced defocusing gives rise to a self-guiding mechanism, which involves a complex time dependent radial energy flow (dynamical spatial replenishment). This energy flow strongly links spatial and temporal dynamics.
One of the most surprising properties of femtosecond filaments is on-axis self-compression, i. e., pulse shortening in the center of the beam during filamentary propagation. For examining the self-compression regime, experimental set-ups use windowed cells, allowing for careful optimization of the pressure that gives rise to maximum self-compression. Here we will investigate numerically the influence of these exit windows on pulse propagation, which distort the spatio-temporal shape of the exiting pulse considerably and seem to destroy self-compression. However, upon subsequent propagation in, e.g., the atmosphere, a self-healing mechanism takes place. We find that again, as the self-compression mechanism itself, this self-healing process is a result of a time dependent radial energy flow.