Self-focusing effect of focused array beams propagating from the space orbit through the atmosphere to the ground

Abstract

For the incoherent beam combination, the self-focusing effect of focused array beams propagating from the space orbit through the atmosphere to the ground is studied. It is shown that the self-focusing effect in the atmosphere becomes stronger as the fill factor increases. When the circumcircle diameter and the fill factor of array beams are fixed, the self-focusing effect in the atmosphere becomes stronger as the element number N decreases. However, for the maximal beam compression case, the self-focusing effect in the atmosphere can assist delivering much more powerful array beams from the space orbit to the ground as N increases, and an array beam has the advantage to deliver powerful laser beam compared with a single laser beam. In particular, an effective design rule for maximal compression without filamentation of transported array beams from orbit to the ground is derived.