Avoiding the tip: spiral optics for robust high power beam shaping of Bessel beams

Bessel Gaussian beams offer unique possibilities in material processing due to their elongated high-intensity line foci. They are usually created using an axicon. Being used with high power, the most critical part of the axicon is its tip, as it is prone to laser-induced damage. Any imperfection of the tip can be the source of aberrations of the focus. Therefore, we propose to apply Laguerre Gaussian beam shaping to circumvent the tip of the axicon altogether. We introduce an optical system consisting of spiral phase plates and an axicon to combine Laguerre and Bessel Gaussian beam shaping. This system is experimentally implemented using custom-made spiral phase plates and a large angle axicon. We characterize and finally apply the system to glass cutting and demonstrate the cleaving of a 2 mm thick glass sample, which results in a high-quality breaking edge with sub-micron roughness.