入射角对飞秒激光诱导金属表面周期性结构的影响

Effects of Incident Angle on Metal Periodic Structures Induced by Femtosecond Laser Pulses

用脉宽为60 fs,频率为1 kHz.中心波长为800 nm的飞秒脉冲激光照射在高纯度的Cu ,Ag, Au金属靶材表面,在损伤阈值附近产生周期性结构,并随着脉冲作用数的增加,产生的规则周期性结构被破坏。研究了人射角度对周期性结构大小的影响,发现在较小角度时,三种金属周期性结构大小几乎没有区别,在较大角度时,三者之间的差别也微乎其微;不同金属的损伤阂值各不相同,因此,认为人射激光的能量密度在较小角度时只影响表面周期性结构的锐利程度,并不影响其大小。并从激光诱导金属表面产生周期性结构的理论出发进行了理论验证。

Abstract Near the damage threshold, the periodic surface structure on pure Cu, Ag and Au produced by femtosecond laser pulses of 60 fs at 1 kHz repetition with the central wavelength of 800 nm is observed by scanning electronic microscope （SEM）. With the number of laser pulses increasing, the structure is damaged obviously. The period of the structure depending on the incidence angle is studied, and it is found that the period of the three metals are almost the same when the incidence angle is small. The difference between each other is still infinitesimal when the incident angle is large. Different metals have different damage threshold, so it is believed that the incident laser energy density at small angle affects the periodic structures＇ sharpness only. It was verified in terms of surface periodic structures theory （SPSs）.