不同场强分布的1064nm激光减反膜损伤特性

Laser damage properties of 1 064 nm anti-reflective films with different electric field distributions

设计了两种具有不同场强分布的1 064nm减反射膜结构,即G/H3L/A和G/M2HL/A。采用离子束辅助沉积技术,在K9基底上制备了薄膜,并对薄膜在强激光下的损伤斑形貌及损伤阈值(LIDT)进行了测量。研究结果表明:薄膜的场强分布不同,其抗强激光的能力也不相同。当两种膜系的电场强度(归一化电场强度平方)在薄膜-空气界面处分别为1.039和0.906时,对不同的激光能量(180,150和120mJ),样品G/H3L/A的表面破损斑尺寸均大于样品G/M2HL/A;两种薄膜的激光损伤阈值分别为12.3J/cm2和14.8J/cm2(激光波长为1 064nm,12ns)。这说明,较小的薄膜-空气界面电场强度,有利于激光损伤能力的提高。因此,对于减反射薄膜,在膜系设计时,采用合理的场强分布,降低薄膜-空气界面的电场强度,可以有效改善薄膜的激光损伤特性。

Two anti-reflective films at 1064 nm with different electric field intensity distributions, namely, G/H3L/A and G/M2HL/A,were designed and prepared on K9 glass sUbstrates by ion beam assistant deposition （IBAD） technique. The damage morphology and laser-induced damage threshold （LIDT） of these films were investigated in this paper. The results indicate that the different electric field intensity distributions of the films may generate different laser damage properties. When the electric field intensity （normalized electric field intensity squared） is 1. 039 and 0. 906 respectively at the interface between layer and air,the damaged area of sample G/H3L/A is always larger than that of sample G/M2HL/A,as the laser incident energy is 180 mJ,150 mJ,or 120 mJ at one pulse. The LIDTs of the samples are 12.3 J/cm2 and 14.8 J/cm2 （1064 nm,12 ns） respectively. It shows that a higher LIDT may be obtained under lower electric field intensity at layer-air interface. Therefore, the damage properties of the films may be improved by lowering the electric field intensity at the layer-air interface during the process of film stack optimization design.