UV-ultrashort pulsed laser ablation of fused silica

The authors report on ultraviolet ultrashort pulsed laser ablation of fused silica and compare the achievable micromachining results to those obtained by using the fundamental emission wavelength in infrared. Ablation in ultraviolet reveals a stable efficiency for increasing fluences, whereas using an infrared beam exhibits a decreasing trend of the ablation efficiency at higher and increasing fluences. In addition, a significant improvement in the surface quality is found by using an ultraviolet wavelength in a fluence range up to 20 J/cm2 compared to infrared, e.g., revealing an Ra of down to 0.45 μm on using the ultraviolet wavelength compared to Ra = 0.56 μm on using infrared at fluences up 15 J/cm2. Moreover, taking advantage of the high available pulse energy, the authors compare the achievable ablation efficiency and surface roughness using a conventionally focused ultraviolet beam and a defocused ultraviolet beam, finding that the defocused ultraviolet beam possesses a processing quality comparable to that of the focused beam. Finally, the authors exemplify the potential of ultraviolet ultrashort pulsed laser ablation by using a Tesla mixer for microfluidic integration of fused silica.