Ultra-thin rapeseed oil-assisted femtosecond laser etching on quartz glass micro-grooves

Liquid-assisted methods can effectively suppress thermal effects, such as recrystallization, micro-cracks, and edge collapses of hard and brittle materials in femtosecond laser processing in air. However, the small and numerous bubbles generated by water solvents seriously affect laser processing efficiency. We have investigated ultra-thin rapeseed oil-assisted (approximately 58μm thickness) femtosecond laser processing of quartz glass microgrooves. Experimental results show that rapeseed oil-assisted laser ablation reduces the adverse effects of bubbles through the bubble coalescence effect but also helps to discharge the bottom debris via the formed micro-jet. According to the ionization model with the Drude equation, the laser intensity to reach the damage threshold of quartz in rapeseed oil is lower than that in air. Based on heat conduction theory, rapeseed oil can effectively reduce the quartz glass's temperature gradient. The ultra-thin rapeseed oil-assisted femtosecond laser etching method has strong potential and important practical significance in etching glass material.