High-precision etching of micro-grooves within double-layer glass via liquid-assisted laser ablation

• Developed a liquid-assisted laser method for one-step double-layer glass etching. • Revealed distinct etching mechanisms for different lasers & upper and lower glass substrates . • Achieved adjustable high-precision micro-grooves at micron depth. • Demonstrated reliable circuit performance using LIPAP techniques. Glass is a highly transparent and chemically stable material with considerable application potential. However, its high hardness and brittleness pose challenges in processing, particularly when creating intricate 2D and 3D microstructures. Traditional processing methods often result in lower precision and poor edge quality. Recent advancements in laser technology, particularly with femtosecond lasers, offer new solutions due to their minimal thermal impact and ability for high-quality cold processing. This paper introduced a novel liquid-assisted laser ablation method, compared the ablation effects of different pulse-width laser sources and achieved single-step etching of double-layer glass. By encapsulating copper sulfate (CuSO 4 ) solution as an absorbent within the double-layer glass, high-precision micro-grooves were successfully etched. The results indicated that micro-groove depth can be controlled by adjusting laser parameters, with femtosecond laser outperforming nanosecond laser in etching quality. This study also delved into the underlying principles, revealing the mechanisms of material modification during femtosecond laser ablation. Furthermore, laser-induced plasma-assisted penetration (LIPAP) technique allowed for filling the micro-grooves with copper paste, in order to create stable surface heating circuits and verify the functionality. This laser double-layer processing strategy offers an effective solution for the precise fabrication of micro-functional devices based on transparent hard and brittle materials.