Direct Laser Ablation of Glasses with Low Surface Roughness Using Femtosecond UV Laser Pulses

In this article, the properties of soda-lime glass after direct laser ablation are studied by utilizing femtosecond UV laser pulses of 206 nm wavelength, 300 fs duration at 50 kHz pulse repetition rate, generated by a solid-state Yb:KGW laser system. The results prove that linear light absorption allows the fabrication of good-quality pits with very low heat-affected zones (HAZ) without any postprocessing. Several sets of pits were ablated with a varying number of laser pulses per spot and different pulse energies. Pits' width, depth, and volume parameter maps that show relations with the number of pulses per spot, laser pulse energy, and fluence are depicted. These maps are useful when considering a suitable set of parameters for the fabrication of diffractive optical or similar devices where low surface roughness is critical. The ablated craters were also inspected with a scanning electron microscope (SEM) which indicates that femtosecond UV laser pulses are capable to achieve a good quality ablation with a low surface roughness of the modified zone.