飞秒激光作用下薄膜的阈值损伤到膜层剥落

在飞秒单脉冲激光损伤HfO_2/SiO_2薄膜样品实验中,随着激光能量密度升高,膜层从缺陷导致的点损伤发展到整层剥落,损伤区域轮廓由模糊变清晰.研究表明,尺度在纳米量级的颗粒缺陷会产生局部的场增强效应,该效应与薄膜干涉场叠加,造成了阈值损伤阶段损伤区域出现大量损伤点,且由于飞秒激光对包括缺陷在内的薄膜材料的本征损伤特性,使其损伤行为较为确定,随着激光能量的提升,薄膜出现更大面积的规则烧蚀区,此时干涉场的作用上升到主导地位,膜层的整层剥落行为掩盖了缺陷的诱导作用.

The evolution of coating threshold damage to peeling off under femtosecond laser irradiation

In the experiment of HfO2/SiO2 coatings damaged by femtosecond single pulsed laser, the evolution of coating ablation along with increase of the laser energy was observed. The research shows that coating defects even in nanoscale can induce local light field intensification, which superposes on the interference field. As a result, the coating damage in threshold phase is mainly controlled by the particle defects even when irradiated by femtosecond laser. Because of the intrinsic damage characteristic of femtosecond laser to the coating materials including the defects of even distribution, the damage thresholds of these coatings are relatively deterministic. With the increase of pulse energy, the outline of damaged area becomes clearer. In this condition, the contribution of interference field is increasingly dominant compared with the local light field caused by defects, and the phenomena of coating spalling cover up the impact of defects.