Creation of micro-holes on glass surface by femtosecond laser through the ejection of molten material

The interaction of femtosecond laser pulses (800 nm, 150 fs, 1 kHz) with the surface of fused silica glass was investigated. The morphology and chemical composition of unirradiated and irradiated glass surfaces and of the material ejected from the surface were examined by secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental results show that (i) femtosecond laser pulses induced damage on the surface of the glass by the formation of micro-holes. Material was ejected from the glass surface during laser irradiation while the glass was melted, (ii) the interaction of the laser beam with glass was initially fast but decreased rapidly with time and eventually no change was observed, (iii) no significant changes in the chemical composition of the irradiated glass surfaces were observed. The chemical composition of the ejected and original material was essentially identical, and (iv) the presence of crystalline phase was detected in the ejected material.