Three-dimensional nanostructuring of transparent materials by the femtosecond laser irradiation

Femtosecond laser is a perfect laser source for materials processing when high accuracy and small structure size are required. Due to the ultra short interaction time and the high peak power, the process is generally characterized by the absence of heat diffusion and, consequently molten layers. Various induced structures have been observed inside glasses after the femtosecond laser irradiation. Here, we report the refractive index change, space-selective valence state manipulation of active ions and precipitation control of nanoparticles by a femtosecond laser in glasses. We have recently observed the three-dimensional nanostructuring such as a nano-grating and a nano-void inside a glass material by the single laser beam irradiation. The self-organized sub-wavelength periodic nanostructures are created by via a pattern of interference between the incident light field and the electric field of the bulk electron plasma wave. The mechanisms of the observed phenomena were also discussed. Furthermore, we observed the space-selective structural-phase transformation from diamond to amorphous structure which has electrically conductive property