Laser ablation of thin composites with low thermal conductivity with pulsed and continuous-wave beams

The thermal response of a material to laser irradiation is governed by its physical parameters, particularly thermal conductivity and thickness, which lead to significant differences in how various material systems interact with lasers with distinct temporal light emission patterns. Understanding this relationship is crucial to select appropriate laser sources across applications ranging from industrial processing to defense. In this study, a model linking the thermophysical properties of a given material with laser operation modes is established. Penetration time is used as the primary evaluation metric to systematically investigate the ablation behaviors of continuous-wave (CW) and pulsed lasers incident on materials with different thermal conductivities. The results showed that CW lasers are more suitable for ablating thick metals with high thermal conductivity, whereas pulsed lasers achieve higher ablation efficiency and shorter penetration times with thin composites having low thermal conductivity because of the significant thermal localization induced by the high instantaneous energy deposition. The results of an experimental evaluation using carbon fiber reinforced polymer further demonstrated that the penetration time of a CW laser could exceed that of an mJ-level pulsed laser by more than an order of magnitude for the same average power density. Our findings also revealed that excessively high pulse energy can reduce ablation efficiency due to plasma shielding effects. This study elucidates the relationship between the thermophysical properties of different materials and the temporal pattern of a laser beam intended to cut through or damage those materials. Thus, our findings provide a theoretical and experimental basis for optimizing laser ablation parameters for different material systems.