Optics and Photonics Society of Iran

In this paper, a comprehensive theoretical model is presented to investigate the whole chain of processes occurring in the interaction of a focused ultrashort laser pulse with fused silica glass. The equations describing the nonlinear propagation of an ultrashort pulse inside transparent material, electron density evolution, heat conduction, and thermo-elasto plastic displacement are respectively solved, and lastly, it is calculated induced refractive index changes inside the material and qualitatively compared with experimental results. The results show that the major induced refractive index changes is negative and located in the center of the profile. In the following, the performed experiments show that increasing the number of incident pulses causes inducing periodic nano-structures in focal region that orientation of the induced birefringence axes depends on the polarization of the incident pulses