Self-reconstruction of femtosecond laser filament after free propagation in linear medium

In the present work we investigated experimentally and numerically the formation and self-reconstruction after an air gap of extremely compressed wave packet — “light bullet” (LB) in process of Near-IR and Mid-IR femtosecond filamentation. We showed that in a normal group velocity dispersion (GVD) regime the maximal width of the air gap, after which LB self-reconstruction occurs, is less than 25 mkm due to strongly divergent LB wave front in the gap. While in the case of anomalous GVD that single-cycle Mid-IR LBs are extremely robust formations and are capable to the complete spatiotemporal self-reconstruction in nonlinear dispersive media after propagation through an air gap up to 1000 µm in free-space regime without dispersion.