Vector Bessel beam polarization control along the propagation direction for efficient stealth dicing

Femtosecond laser stealth dicing technology demonstrates broad application in precision machining of transparent dielectrics, where laser polarizations play a decisive role in the processing. In this study, we propose a method to generate a vector Bessel beam with polarization tunable along the propagation direction for high-quality and high-precision z-cut α-quartz stealth dicing. We reveal that the femtosecond laser Bessel beam with left-handed circular polarization (LCP) exhibits maximum energy deposition inside α-quartz, while linear polarization demonstrates higher precision in surface ablation. The modification depth of linearly polarized laser processing varies with the angle between the scan direction and polarization orientation, whereas circularly polarized laser processing exhibits no directional dependence. We design a vector Bessel beam combining linear and left-handed circularly polarized components along the propagation direction for highly uniform stealth dicing. Assisting with hydrofluoric acid (HF) etching, arbitrarily curved structures can be fabricated with high precision. The roughness of the sidewall can reach Ra 0.026, and the maximum aspect ratio can be 4413:1. Our method provides an innovative solution for efficient stealth dicing of z-cut α-quartz, showing significant potential for industrial applications in quartz sensor manufacturing.