Generation of concatenated long high-density plasma channels in air by a single femtosecond laser pulse

We experimentally demonstrate a stable and reproducible generation of long concatenated high-density plasma channels in air by a single femtosecond laser pulse. Each segment of the plasma channel is created by a plasma filament left in the wake of the same single high power laser pulse. Our method enables a control of a few millimeters over the position of each segment as well as exact temporal synchronization between them. The combined plasma channel can extend up to several meters long. The plasma density along the entire concatenated plasma channels is measured to be above 10¹⁵cm^-3. The demonstrated approach can be further extrapolated to a higher number of filament segments, thus to much longer high-density plasma channels.