Shape- and size-controllable microstructure on glass surface induced by femtosecond laser irradiation

Controllable microstructures are formed on a glass surface after irradiation of a focused 800 nm, 250 KHz femtosecond laser beam. Field-emission scanning electron microscope and 3D measuring laser microscope images reveal that the induced structures are circular and linear protuberances and can be controlled from 10 microm to hundreds of micrometers in width, and from 1 microm to tens of micrometers in height. The protuberance structure is proposed to be formed as a consequence of the laser-induced high temperature and pressure owing to linear and nonlinear absorption near the laser focal point, and low softening and melting temperature of the glass sample.