Femtosecond Filaments and Air Waveguides Generated by TW Vortex Beams

Controlling the filamentation of ultrashort and intense near-infrared laser pulses in air is crucial for many applications. For this purpose, tuning the phase of the laser beam provides a convenient way to change its far field intensity distribution. In particular, a vortex beam generated by a spiral phase plate can produce a stable ring profile with a rotating spatial phase [1], [2]. This phase momentum makes it more suitable for telecommunications through atmospheric turbulences [3] and allows the organization of multiple filaments in a cylindrical shape that is optimal to guide electromagnetic waves [4].