Formation mechanism of self-organized nanogratings induced by femtosecond laser pulses on titanium surface

In this paper, we demonstrate the formation of self-organized periodic nanogratings on the titanium surface under the irradiation of a single-beam femtosecond laser. We vary various laser parameters such as the laser fluence and the number of laser pulses in each spot to fabricate self-organized nanogratings on the titanium surface. We investigate that the direction of the nanogratings is perpendicular to the direction of laser polarization. We also report on the dependence of the nanogratings' period, produced on titanium surface, on the laser fluence and the number of irradiated laser pulses in each spot. Nanogratings' period show increasing trend with the increase of the laser fluence, whereas show decreasing trend with the increase of the number of applied laser pulses. Furthermore, we briefly explain the formation mechanism of the self-organized periodic nanogratings, produced on the titanium surface. The reasons behind the dependence of nanogratings' period on the laser fluence and the number of laser pulses are explained as well. The self-organized nanogratings are mainly produced due to the interaction of the high-intensity incident laser beam and the laser induced plasma waves. Above certain threshold energy, phase explosion takes place, which in turn causes the formation of self-organized nanogratings on the titanium surface.