LAUSR

Due to their unique optical properties, Bi-doped glasses have a great potential for the development of new tunable laser sources. Particular attention is given to high-silicate Bi-doped glasses as active media for fiber lasers and optical amplifiers, capable to operate at the second and the third near-infrared (NIR) transparency windows. Although significant practical advances have been achieved in this area, the origin of the NIR luminescence remains unclear. In the present paper, a set of glasses 95.5SiO2–4.5Al2O3–xBi2O3 (x = 0; 0.005; 0.01; 0.05; 0.1; 0.2) were synthesized using a conventional melt-quenching technique and investigated using a multiscale approach. Variation of the NIR emission was correlated with the change of other optical properties, structure and bismuth redox, supported by fluorescence/absorption, Raman, and XANES experimental studies, respectively. It was found that redox of bismuth shifted toward the formation of more reduced Bi species with the decrease of the dopant level. Based...