Transient absorption and luminescence spectra of K9 glass at sub-damage site by ultraviolet laser irradiation

•Transient absorption and luminescence spectra at sub-damage site of K9 glass by laser irradiation at 355 nm are presented.•As the energy density increases to 2.54 J/cm2, the absorption intensity reaches to about 0.2.•The mechanism of two-photon ionization mainly plays a critical role at sub-damage site.•Intensity of Raman spectra is very high at low energy density and decreased with respect to high energy density.

Transient absorption and luminescence spectra at sub-damage site of K9 glass by laser irradiation at 355 nm are presented. The dependence of transient absorption on laser energy and number of pulses was investigated. As the energy density increases to 2.54 and 3.18 J/cm2, the transient absorption intensity reaches to about 0.20 range from 400 to 480 nm. With the increase of number of pulses the process of residual absorption appears, which can be used to explain the fatigue effect of K9 glass. The defects in K9 glass were investigated by fluorescence and Raman spectra. The fluorescence band centered at about 410 nm is attributed to oxygen deficiency centers. The mechanism of two-photon ionization plays a critical role at sub-damage site. Compared to the Raman spectra of pristine site, intensity of Raman spectra is very high at a lower energy density, while it decreased at a higher energy density.