The evolution of surface morphology of tungsten irradiated by single-beam femtosecond laser pulses is investigated. Ripplelike periodic structures have been observed. The period of these ripples does not show a simple relation to the wavelength and angle of incidence. The orientation of ripples is aligned perpendicularly to the direction of polarization for linearly polarized light. Surprisingly, we find that the alignment of the ripple structure turned left or right by 45° with respect to the incident plane when using right and left circularly polarized light, respectively. The period of the ripple can be controlled by the pulse energy, the number of pulses, and the incident angle. We find a clear threshold for the formation as a function of pulse energy and number of pulses. The mechanism for the ripple formation is discussed, as well as potential applications in large-area structuring of metals.
© 2007 Optical Society of AmericaFull Article | PDF Article
T. Z. Kosc, A. A. Kozlov, and A. W. Schmid
Opt. Express 14(22) 10921-10929 (2006)
Quan-Zhong Zhao, Stefan Malzer, and Li-Jun Wang
Opt. Express 15(24) 15741-15746 (2007)
Hideo Iwase, Satoshi Kokubo, Saulius Juodkazis, and Hiroaki Misawa
Opt. Express 17(6) 4388-4396 (2009)