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

Area of Science:

• Materials Science
• Laser Physics
• Nanotechnology

Background:

• Femtosecond laser stealth dicing is crucial for transparent dielectrics.
• Laser polarization significantly impacts machining precision.
• Z-cut α-quartz requires advanced dicing techniques for high-quality fabrication.

Purpose of the Study:

• To develop a tunable polarization vector Bessel beam for high-precision stealth dicing of z-cut α-quartz.
• To investigate the influence of different laser polarizations on energy deposition and surface ablation.
• To achieve uniform dicing and fabricate complex structures with high aspect ratios.

Main Methods:

• Generation of a vector Bessel beam with polarization tunable along the propagation direction.
• Utilizing femtosecond laser Bessel beams with linear and left-handed circular polarization (LCP).
• Combining linear and LCP components for uniform stealth dicing, assisted by hydrofluoric acid (HF) etching.

Main Results:

• Left-handed circular polarization (LCP) maximizes energy deposition in α-quartz.
• Linear polarization offers higher precision in surface ablation, with depth dependent on polarization angle.
• Circularly polarized laser processing shows no directional dependence.
• A combined vector Bessel beam enabled highly uniform stealth dicing.
• Achieved sidewall roughness of Ra 0.026 and a maximum aspect ratio of 4413:1.

Conclusions:

• The proposed vector Bessel beam method offers an innovative solution for efficient stealth dicing of z-cut α-quartz.
• The technique allows for fabrication of arbitrarily curved structures with high precision.
• Demonstrates significant potential for industrial applications, particularly in quartz sensor manufacturing.