Post-Filamentation Light Channels in Air

Abstract—The results are presented of the experimental study of spatial characteristics of postfilamentation light channels in air formed by femtosecond pulses of a Ti:Sapphire laser with different energy for focused and collimated beams. It is found that the angular divergence of channels is dozens of times lower than the angular divergence of a beam as a whole for focused beams in the far zone from the filamentation region. The angular divergence of the channels first significantly decreases with an increase in the pulse energy and then saturates. For collimated beams, at a fixed distance from the source, an increase in the pulse energy also leads to stabilization of the channel cross section.