Nonlinear coloration and damage of wide-gap glasses by femtosecond laser at 0.85 um

Abstract

The processes arising in glasses as an example of solid dielectrics under high-power femtosecond laser radiation have been investigated. In the investigation samples of fused silica were used as well as a wide selection of commercial borosilicate glasses K8 (Russia) and BK7 (USA) which have the band gap near 6 eV. The glass samples were irradiated with the output of a laser system allowing the production of laser pulses at 0.85 micrometer wavelength and duration approximately 10 -13 s. It is found that color centers formation and intrinsic luminescence of borosilicate glasses are observed under high-power femtosecond radiation at 0.85 micrometer. These processes result from supercontinuum generation in the bulk glass and are followed by two-photon absorption of the short-wavelength part of this supercontinuum. These same processes lead to the damage of glasses under conditions of intensive ionization of material matrix, and show that the damage process is not connected with avalanche ionization. Show more