Elongation of the transverse profile of the optical needle using nondiffracting airy beams and laser microprocessing of glasses

Significant progress in laser beam shaping has been driven by scientific and industrial demands. Nondiffracting beams, such as Bessel beams, are widely used for communication, imaging, and laser microprocessing due to their self-healing and resistance to diffraction. However, controlling the elongation of an optical needle's transverse profile remains a key requirement. This study proposes using nondiffracting Airy beams and a binary phase mask to achieve this control. Performance is evaluated through numerical simulations and experimental assessments, focusing on metrics like the major-to-minor axis ratio, needle length, and stability. A flat optical element is created using geometrical phase induced by nanogratings inscribed with a femtosecond laser. The geometrical phase element's performance is validated through laser microprocessing of transparent glasses, with reported experimental results.