Effect of sodium on the laser spectrometric parameters and C-band optical gain of erbium doped zinc phosphate glasses With deep gratitude and recognition, in honor of Professor Giancarlo Righini, who his work is a shining example in the field of photonic glasses

This work investigates the effect of sodium incorporation on the laser spectroscopic properties and C-band optical gain of Er3+-doped zinc phosphate glasses. Two glass compositions – zinc phosphate (ZPO) and sodium-zinc phosphate (NZPO) – were synthesized and characterized through absorption and emission spectroscopy. The Judd–Ofelt theory was applied to determine the intensity parameters ( Ω 2 , Ω 4 , Ω 6 ), from which radiative properties such as spontaneous emission probabilities, branching ratios, and lifetimes were derived. Emission and absorption cross-sections were calculated, and the theoretical on–off gain was estimated and compared to experimental measurements. The results reveal that NZPO exhibits enhanced optical performance, including higher σ e , broader effective bandwidth, and greater theoretical and experimental gain values. The increase in Ω 2 and Ω 6 in NZPO indicates stronger ion-ligand interaction and improved radiative efficiency, making sodium-zinc phosphate glasses promising candidates for C-band optical amplifiers and laser applications.