Generation of flat-top pulse by means of step gratings

A simple method for generating flat-top pulse by means of step gratings is presented. Flat-top pulse specifications depend on the structural parameters of the step gratings. The results show that a short Gaussian-shaped femtosecond laser pulse can be shaped to be a long flat-top pulse by ensuring sufficient step level number and proper step height.

► Step grating is used for pulse shaper.
► Short Gaussian-shaped incident pulse can be shaped to be a long flat-top diffraction pulse.
► Dependences of the flat-top pulse on the structural parameters of the step gratings are explored.