Investigation on fiber laser irradiation of transparent polycarbonate

The study aims to understand the carbonization mechanism when an ns NIR transparent fiber laser beam irradiation of polycarbonate (PC) instead of irradiation using a UV laser beam or ultrashort pulsed laser beam. It reveals that PC can be decomposed with an ns transparent 1064 nm laser beam. The laser fluence threshold under which to cause ablation in PC was not a constant value. The threshold decreased as the scanning pulse number increased. The threshold fluence was above 2.9 J/cm2 at irradiation with 10 pulses. The threshold fluence was above 11.6 mJ/cm2 at irradiation with 2 pulses. The optical transmittance of PC was decreased under laser irradiation. The optical transmittance was reduced by 50% and 90% at laser fluence of 2.9 J/cm2 and 11.6 J/cm2, respectively, at irradiation with 15 pulses. In addition, x-ray photoelectron spectroscopy measurements show that the C/O ratio was reduced 20.8% and 33.2%, respectively. The water contact angle was reduced due to the carbon loss at the PC surface. Inside marking of PC produced a darker contrast than surface marking due to that the carbon was lost at the surface, in contrary, carbonate concentration remained when marking inside the bulk of PC.