Yb 3+ doped silica sol-gel glass powders were prepared with different concentrations of SiO2, Al2O3 and P2O5 in order to understand the impact of the glass composition on the Yb 3+ emission properties. In this paper, we clearly show that not only the Al/P ratio but also the SiO2 content have an impact on the Yb 3+ spectroscopic properties. Our results provide new insight on the real impact of the composition on the spectroscopic properties of Yb 3+ doped sol-gels: we demonstrate that an increase in the Al2O3 content at the expense of P2O5 leads to an increase in the intensity of the emission at 1000nm of the Yb 3+ ions whereas an increase in the SiO2 content decreases it. We clearly showed that the inexpensive sol-gel approach can be easily used when investigating new Yb 3+ doped silica glasses
