Spectroscopic properties of Tm3+/Al3+ co-doped sol–gel silica glass

Abstract

Tm3+/Al3+ co-doped silica glass was prepared by sol–gel method combined with high temperature sintering. Glasses with compositions of xTm2O3–15xAl2O3–(100−16x) SiO2 (in mol%, x=0.1, 0.3, 0.5, 0.8 and 1.0) were prepared. The high thulium doped silica glass was realized. Their spectroscopic parameters were calculated and analyzed by Judd–Ofelt theory. Large absorption cross section (4.65×10−21cm2 at 1668nm) and stimulated emission cross section (6.00×10−21cm2 at 1812nm), as well as low hydroxyl content (0.180cm−1), long fluorescence lifetime (834μs at 1800nm), large σem×τrad (30.05×10−21cm2ms) and large relative intensity ratio of the 1.8μm (3F4→3H6) to 1.46 (3H4→3F4) emissions (90.33) are achieved in this Tm3+/Al3+ co-doped silica glasses. According to emission characteristics, the optimum thulium doping concentration is around 0.8mol%. The cross relaxation (CR) between ground and excited states of Tm3+ ions was used to explain the optimum thulium doping concentration. These results suggest that the sol–gel method is an effective way to prepare Tm3+ doped silica glass with high Tm3+ doping and prospective spectroscopic properties.