Effect of co-dopants on the spectral property of Yb3+ doped silica glasses at 1018 nm

To enhance the laser performance of Yb 3+ -doped silica fiber for 1018-nm tandem-pumped technology, three series of Yb–Al, Yb-Al-P, and Yb–P co-doped silica glasses with a large size, high homogeneity, and precise composition control were prepared using a sol-gel method combined with high-temperature sintering technology. In addition, the effects of Al3+ and P5+ co-dopants on the absorption and emission properties of Yb3+-doped silica glasses at 1018 nm were investigated systematically. The normalized spectral characteristics of the glass samples with different doping series at 1018 nm were compared horizontally, and the results showed that the normalized emission intensity of the Yb-P-doped silica glass series samples at 1018 nm was significantly better than that of the other series. The emission subpeak was located near 1018 nm when the content of doped P was 5 mol%, and the position of the subpeak gradually blue-shifted as the content of the doped P increased. Using Raman spectroscopy combined with ultra-low temperature electron paramagnetic resonance (4K), the coordination environment of Yb 3+ was accurately resolved at the atomic scale. In Yb 3+ -doped silica glasses, the coordination environment of Yb 3+ was extremely different from the introduction of Al 3+ and P 5+ , which is consistent with the influence of Al 3+ and P 5+ on the spectral properties of Yb 3+ at 1018 nm. • Three series of Yb-Al, Yb-Al-P and Yb-P co-doped silica glasses with large-size, high homogeneity and precise composition control were prepared by modified sol-gel method. • High concentration of single P-doping can blue-shift the emission sub-peak of Yb 3+ ions to 1018 nm, which effectively enhances the spectral properties of Yb 3+ ion at 1018 nm. • Based on crystal filling and asymmetry theory, the intrinsic connection between the Stark splitting of Yb 3+ ions and the 1018 nm emission spectrum were explained. • The coordination environment of Yb 3+ at the atomic scale was precisely analyzed, and the mechanism of the effect of Al 3+ and P 5+ co-doping on the spectral properties of Yb 3+ at 1018 nm was revealed.