Orientation-controllable self-organized microgratings induced in the bulk SrTiO₃ crystal by a single femtosecond laser beam

Self-organized microgratings were induced in the bulk SrTiO₃ crystal by readily scanning the laser focus in the direction perpendicular to the laser propagation axis. The groove orientations of those gratings could be controlled by changing the irradiation pulse number per unit scanning length, which could be implemented either through adjusting the scanning velocity at a fixed pulse repetition rate or through varying the pulse repetition rate at a fixed scanning velocity. This high-speed method for fabrication of microgratings will have many potential applications in the integration of micro-optical elements. The possible formation mechanism of he self-organized microgratings is also discussed.