Ultrafast laser processing of glass-phase materials - mathematical simulation

摘要

Glass-phase materials, such as glass-carbon, ceramics etc., are a wide class of substances applied in electronic industry. These materials often need special technologies for their processing. Unlike traditional methods of micromachining, focused ultrashort laser pulses of sufficiently high fluence makes it possible not only to avoid the majority of side effects, including temperature, but also to create a qualitatively new laser technology for "hard materials". When using ultrafast lasers in micromachining processes it is necessary to account the possible negative effects that occur in the processing of brittle materials. Removing material from the surface in cold ablation process caused by laser light, in such a short period of time with such a high rate, creates the area of high pressure in the interaction zone that could cause a microdamage of brittle materials. To study the stress-strain state arising in brittle materials under the influence of ultrafast lasers, the special physical-mathematical model of the process was formulated. As a measure of the mechanical action of laser radiation on the processed material in cold ablation the reactive force was taken. As a mechanical reaction of the treated glass-carbon substrate a back pressure generated by the reactive force was considered. Brittle materials suffer plastic deformation, as a rule, only in the areas of high-temperature heating. Hence, in case of picosecond treatment in cold ablation process the material, from a mechanical point of view, was seen as a perfectly elastic up to its destruction. From a geometrical point of view, the processed object was presented in the form of a thin rectangular plate, loosely founded on the elastic base.