Parametric control of propagation characteristics in ultrafast laser Bessel beams modulated by axicon lenses: a simulation study

Abstract Ultrafast laser Bessel beams exhibit significant potential in micro/nanofabrication due to their unique non-diffracting and self-healing properties. However, the multi-parameter coupling mechanisms governing their propagation and modulation remain insufficiently studied. This research establishes a theoretical model incorporating wavelength, beam size, and axicon parameters, complemented by numerical simulations, to systematically elucidate the propagation dynamics of ultrafast laser Bessel beams. Key findings include: The maximum non-diffraction distance demonstrates wavelength insensitivity, exhibits a linear dependence on the incident beam radius, and inversely correlates with the axicon apex angle and refractive index. The central lobe radius scales linearly with wavelength and inversely with axicon parameters, while remaining independent of the incident beam radius. Building upon these insights, a systematic parameter-decoupling approach is proposed: independent adjustment of the incident beam radius and axicon parameters enables precise control over propagation distance and machining resolution, respectively. Specifically, theoretical predictions indicate that employing a large incident beam radius with a small axicon angle can achieve non-diffracting propagation exceeding 1 m, whereas combining short-wavelength lasers with large apex angles yields near-micron-scale machining resolution (∼2.26 μ m). These findings provide critical theoretical guidance for optimizing ultrafast laser precision machining systems, with broad applications in semiconductor device manufacturing and micromachining.