利用50 MHz和1 MHz的重复频率光子晶体光纤飞秒激光分别在45#钢表面产生了微浮雕结构。实验发现微浮雕结构的高度和宽度与入射激光功率、激光扫描速度以及脉冲重复频率有关。通过调整这些参数, 可以实现对微浮雕形态结构的精确控制。对微浮雕结构的产生机制进行了初步分析, 发现微浮雕结构的产生与高重复频率飞秒激光的热积累效应有关。热积累导致了45#钢的表面熔化, 在液体表面张力和温度梯度力共同作用下, 产生了微浮雕结构。

Micro-relief lines were formed on the surface of 45# steel by photonic crystal fiber femtosecond laser with a repetition rate of 50 MHz and 1 MHz respectively. The heights and the widths of the micro-relief lines were affected by the input laser power, the laser scanning velocity and the pulse repetition rate. The specific structure of the micro-relief can be controlled by properly adjusting these parameters. The mechanism for the formation of the micro-relief was also analyzed preliminarily. The heat accumulation of the high repetition rate femtosecond laser induces the surface melting of the 45# steel, which results in the micro-relief structures by the combination of the liquid surface-tension and the temperature gradient.