A highly efficient method of dehydroxylation and fining of Nd phosphate laser glasses

Abstract We describe herein a method that shows to be highly efficient in the dehydroxylation and fining process of phosphate glasses and that has been tested on the Nd‐doped 15Na 2 O‐15K 2 O‐20BaO‐50P 2 O 5 metaphosphate composition. The method consists of a two‐step procedure: first, the batch is melted in a ceramic crucible; then, the obtained glass is re‐melted under a constant N 2 flow, while being placed inside a graphite crucible with a much bigger surface area as compared to its depth. This allows the melt to be spread over the crucible area resulting in a relatively thin layer with a high area in contact with the atmosphere at the temperature of remelting. It has been demonstrated that the water content decreases with both temperature and time length and that the glass samples obtained are completely free of bubbles and stria showing very high chemical and optical homogeneity. This method employed, has been proven to be very effective, as evidenced by the great increase in the lifetime of Nd 3+ luminescence––reaching a maximum of 380 μs‐which is much higher than the one measured in the untreated glass.