Remote air photonics based on high-repetition-rate Yb:YAG laser filamentation

Many atmospheric laser applications rely on the long-range propagation of laser pulses. In this work, we demonstrate a method for remotely shaping laser beams by generating stable gaseous optical elements in air. These structures emerge from controlled gas dynamics driven by filamentation of a kilohertz picosecond Yb:YAG laser. We observe a new, to the best of our knowledge, air photonic structure-a tunable defocusing lens-attributed to the cumulative effects of low-density channels. Additionally, we show that self-focusing of a collimated Laguerre-Gauss beam can form a permanent air waveguide of 6 mm extending over more than 20 meters. Numerical simulations of the gas dynamics reproduce the observed features of a continuous wave (CW) probe beam injected into these optical structures. This air photonics strategy has broad potential applications in laser power modulation and atmospheric optics.