Laser Ablation of Optical Glasses in the Linear and Non-Linear Absorp tion Regime Using Ultrashort Pulsed Laser Radiation from Deep UV to IR

An alternative approach to conventional fabrication methods for optical components is the laserbased process chain.In that case, precise form generation can be achieved using ultrashort pulse (USP) laser ablation.Precise control of the ablation depth and surface roughness is a crucial requirement for optical applications.Current developments in USP laser beam sources lead to an increase in output power, enabling high harmonic generation with sufficient pulse energy for the ablation of glass materials.Optical glasses, depending on their specific chemical composition, show a drop in transparency in the UV-range.In this paper, the influence of the pulse duration, exemplary for 200 fs and 8 ps, on the ablation behavior of the optical glasses N-BK7 and P-SF69 is investigated comparing an IR-wavelength of 1030 nm to deep-UV-wavelengths of 257-266 nm.In contrast to IR-ablation, where the ps-pulse duration results in a more efficient ablation compared to fs-pulses, the ablation efficiency of N-BK7 is independent of the pulse duration in DUV.Furthermore, the surface roughness can be reduced to Sa < 0.14 m using DUV laser radiation.The ablation behavior of P-SF69 is melt-dominated, resulting in a smooth roughness down to Sa = 45 nm, near to optical quality.