Phase shift map around the laser filaments, measured at different propagation distances z, 10 μs after the laser pulses, for (a) a laser pulse at 1030 nm with an energy of 120 mJ ; (b) a dual-color laser pulse of 66 mJ at 1030 nmand 54 mJ at 515 nm. (c) Still image of the filament between the two electrodes of the HV generator without applied voltage on the electrodes. Position z = 0 corresponds to the center of the image. The laser comes from the left.