Effect of UV irradiation on photo-thermo induced nucleation of PTR glass

Volume Bragg gratings based on PTR glass are widely applied in high-power laser systems because of its good Bragg selection, high diffraction efficiency and high laser damage threshold. In this work, the photo-thermo induced nucleation mechanism of PTR glass was studied by comparing the absorption spectra of PTR glass before and after UV irradiation and nucleation heat treatment with Gaussian decomposition method. The results show that: the Ag⁰ atom formed by UV irradiation tends to be saturated at the irradiation dose of 1J/cm² ; under the same irradiation dose, the irradiation power has no obvious effect on the number of Ag⁰ atoms, but it will change the the number of free electrons in glass matrix; after UV irradiation and nucleated at 460°C for 2h, the photosensitivity of PTR glass will reappear and AgBr clusters will be dominant in the silver micelles.