Controlling TW-laser pulse long-range filamentation in air by a deformable mirror.

The results of experiments and theoretical modeling of the multiple filamentation of terawatt-power femtosecond laser pulses on a 137 m long air path are presented. We use a multielement optical setup consisting of a Galilean telescope and a deformable bimorph mirror, which allows construction for the desired pulse wavefront at the optical path entrance. By introducing controlled aberrations of the pulse phase profile, we demonstrate the wide-ranging manipulations on the position and spatial structure of the filamentation region. For the first time, to the best of our knowledge, the stable wide-aperture (5 cm in diameter) ring-shaped spatial lattice of high-intense light channels is experimentally realized, which can persist over hundreds of meters in air.

Investigation of laser-induced destruction of droplets by acoustic methods.

Experimental investigations of acoustic signals generated by individual laser-irradiated water droplets are reported. The dependence of droplet destruction thresholds on droplet radius and radiative heating rate is determined. A theoretical explanation of our experimental results is provided in terms of a model that includes the processes of droplet evaporation and fragmentation in response to intense laser heating.