Comparison of the ablation behavior of polymer films in the IR and UV withnanosecond and picosecond pulses

Experiments are performed to compare the ablation behavior in the IR and UV spectral regions of a doped standard polymer, PMMA, and a specially tailor ed photopolymer, i.e., a triazene copolyester, to elucidate the underlying mechanisms. The results are discussed in light of current theories about ph otochemical and photothermal pathways of ablation. Further experiments are performed with nanosecond and picosecond pulses to study the impact of puls e length on the material. From the failure to induce ablation in the IR by doping the specialty polymer with an optical molecular heater we conclude t hat etching in the UV of this compound is mainly governed by a photochemica l process. This result is contrasted by successful ablation of doped PMMA i n the IR via a thermal unzipping mechanism. With respect to practical appli cations, the results show convincingly that the presence of an absorbing ch romophore in the polymer is a prerequisite for achieving high-resolution st ructuring, since molecular absorption is required for an efficient distribu tion of incorporated photonic energy.