Aluminum co-doping of soda-lime silicate glasses: Effect on optical and spectroscopic properties

One of the limits of using silicate glasses as a host for Er3+ is the emission bandwidth, which is smaller than in the case of other oxide glasses, such as phosphates and tellurites. The bandwidth can be increased by adding aluminum to the composition. Here we present an experimental investigation of the effect of increasing aluminum content on optical and spectroscopic properties of this glass. Glass samples were prepared by melting at 1550 °C reagent grade SiO2, Al2O3, Na2CO3, K2CO3, CaCO3, (NH4)3PO4 and Er2O3; Al2O3 concentration ranged from 0.99 to 20 mol%. Both heating and cooling rates were equal to 0.17 °C s−1. Measurements of the fluorescence bandwidth were then made and as a function of alumina content. Judd-Ofelt analysis was performed and calculated radiative lifetimes were compared with experimental ones. Planar waveguides were also fabricated by using ion-exchange technology, and some optical properties measured by the prism coupling technique. These waveguides had losses of the order of 1 dB/cm at 635 nm.