Simulation and experimental investigation of the surface morphology formation mechanism of a D-shaped fiber processed using a pulsed CO2 laser

Abstract

Traditional D-shaped optical fibers are manufactured using mechanical polishing or chemical corrosion techniques, which inevitably introduce sub-surface defects or impurities. In this study, a new D-shaped optical fiber manufacturing method using CO2 laser ablation technology is proposed. Laser ablation technology is a complex multi-physical coupling process involving phase changes. To fully understand the surface morphology formation mechanism during CO2 pulsed laser processing, a three-dimensional numerical model and experimental analyses were used to elucidate the relationship between the fiber surface temperature distribution, surface morphology evolution, processing quality, processing efficiency, and laser parameters. The simulation results showed that the residual temperature between laser pulses was lower than the structural transition temperature of the material, and the simulated morphology was consistent with the experimental results. Moreover, the overlapping spot energy resulted in the processed surface exhibiting a periodic ripple structure. The ablation depth was proportional to the pulse width and inversely proportional to the scanning speed. In addition, different laser pulse widths had almost no effect on the roughness and flatness of the processed surface, but the laser scanning speed had a significant impact on both indexes. These results can guide the optimization of CO2 laser processing methods.