Filamenting-ring-Airy-beam femtosecond pulse in air at 10 m through quasi-Gaussian beam modulation with a dedicated phase plate

Femtosecond laser filamentation in air presents significant potential for atmospheric scale applications, including remote sensing and lightning control. However, projecting a filament over large distances remains a challenge due to the complex nonlinear propagation dynamics of high-intensity femtosecond pulses. This work demonstrates the generation of an intense ring-Airy-beam femtosecond pulse in air, employing a specially designed phase plate that converts an input quasi-Gaussian beam into the Fourier transform of a ring Airy beam at the front focal plane of a Fourier lens. The high damage threshold of the phase plate enables the corresponding near field of the ring Airy beam at the rear focal plane of the lens to reach a tens-of-gigawatt peak power. This near field subsequently evolves, at a distance of 10 m, into an ionizing filament, capable of ablating an aluminum plate and performing laser-induced breakdown spectroscopy (LIBS). Extending the cm-scale propagation of a ring Airy beam in liquids or glasses, as reported in previous works, to the 10-meter scale with the generation of an ionizing filament, represents a crucial step toward real-world applications of remote LIBS with ring-Airy-beam femtosecond pulses. Experimental observations show a filament length of two meters, corroborating the numerical simulation and expanding the potential to applications that necessitate a long plasma channel. Further numerical simulations indicate the feasibility of controlling the starting point of a filament beyond 100 meters by increasing the focal length of the Fourier lens, opening avenues for fascinating applications in remote sensing and beyond.