Fabrication of nano-holes with tunable axial morphology via ring-lens-tailored Bessel beams

This study presents a laser-based technique for fabricating nano-holes with tunable axial morphology on fused silica using ring-lens-tailored Bessel beams.Unlike conventional axicon-based Bessel methods, this approach effectively controls the beam's axial intensity peak by simply adjusting the ring-lens radius (R).By combining theoretical simulation and experimental validation, we demonstrate that the nano-hole morphology can be precisely tuned by modulating the beam's initial energy peak.A taper entrance can be formed, with the taper angle effectively controlled within 52°by adjusting R from 1.25 to 2.50 mm.When R exceeds 2.50 mm, the axial energy distribution becomes uniform and leads to the disappearance of the taper, resulting in a standard cylindrical hole and offering a clear process window for controlling the nano-hole morphology.This single-pulse ablation method advances precision nano-manufacturing by enabling the efficient fabrication of customized nano-holes, with potential applications in photonics, microfluidics, and other nano-engineering fields.