Effect of AlPO4 join concentration on optical properties and radiation hardening performance of Yb-doped Al2O3-P2O5-SiO2 glass

A series of Yb-doped silica glasses containing equimolar amounts of P2O5 and Al2O3 were prepared using a sol-gel method combined with high-temperature sintering. Raman spectroscopy confirmed the formation of AlPO4 join with a P/Al ratio of 1. However, for a P/Al ratio slightly larger than 1, both the AlPO4 join and PvO bond are formed. Based on the absorption, emission spectra, and electron paramagnetic resonance measurements, it was determined that the increase of the AlPO4 join concentration in Yb-doped silica glass leads to (i) a decrease in the refractive index with a factor of 1.1005 x 10(-4) (which allows for a low numerical aperture facilitating single-mode laser), (ii) the sustained spectroscopic properties of Yb3+, (iii) a decrease in Yb cluster concentration, and (iv) an improved radiation hardening performance (beneficial to high-power space lasers). These results suggest that Yb-doped Al2O3-P2O5-SiO2 glass with an appropriate concentration of AlPO4 join has potential applications in high-power space fiber lasers. Published under license by AIP Publishing.