Observation of spontaneous self-channeling of light in air below the collapse threshold.
We report the observation of the self-guided propagation of 120 fs, 0.56 mJ infrared radiation in air for distances greater than 1 m. In contrast with the known case of filamentation, in the present experiment the laser power is lower than the collapse threshold. Therefore the counterbalance between Kerr self-focusing and ionization induced defocusing as the stabilizing mechanism is ruled out. Instead, we find evidence of a process in which the transversal beam distribution reshapes into a form similar to a Townes soliton, with the particularity of a very high stability. We include numerical support for this conclusion.
Ruiz
C
C
Departamento de Fí sica Aplicada, Universidad de Salamanca, E-37008 Salamanca, Spain.
San Román
J
J
Méndez
C
C
Díaz
V
V
Plaja
L
L
Arias
I
I
Roso
L
L