Laser processing technologies are vastly improving due to growing demand of the glass microfabrication. While comparing different glass processing technologies, the throughput, strength and quality of the fabricated parts should be considered. However, the measured strength value of the sample depends on the testing setup, loading rate and sample dimensions. For this reason, most of the measured strength values are incomparable between different research groups. In this work, the top-down cutting in the air (TDC) and assisted with a water (WATDC) layer using picosecond pulses and bottom-up cutting approach using picosecond (ps-BUC) and nanosecond (ns-BUC) pulses were investigated. The surface quality, subsurface damage, sidewall quality and the four-point bending strength of 1 mm thick specimens were assessed.
Lowest sidewall roughness and best front surface quality was achieved using the top-down cutting techniques. However, the quality of the bottom surface was poor, with speckled and subsurface modifications. On the contrary, speckled surface and volumetric modifications were absent in the bottom-up techniques. However, the surface quality of ns-BUC technique was rather poor, with 100 µm mean maximum damage width. This value was considerably reduced when using picosecond pulses.
Although TDC had highest visual quality, its flexural strength was quite low because of the intra-volume modifications. Therefore, sidewall roughness was not sufficient enough to evaluate the strength of the samples. The highest flexural strength of 134 MPa was measured for the front side of the samples cut with WATDC technology.