High-performance multiparametric luminescent thermometer: Dy<SUP>3+</SUP>-doped sodium alumino-borate glass

This work presents a comprehensive study of high-performance multiparametric luminescent thermometry using Dy3+-doped sodium alumino-borate glass. The glass was synthesized via the melt-quenching method and characterized structurally and optically. Temperature-dependent luminescence properties were investigated, focusing on the luminescence intensity ratio (LIR) of thermally coupled Dy3+ transitions, as well as emission bandwidth and line shift. The Judd-Ofelt model was applied to interpret the thermometric behaviour, showing excellent agreement with experimental results. While the luminescence lifetime remained temperature-invariant, making the material unsuitable for lifetime-based thermometry, steady-state spectral features provided high sensitivity and precision. Multiparametric approaches, including multiple linear regression (MLR) and sensor fusion (SF), were employed to combine different readouts, resulting in enhanced temperature resolution and robustness. The sensor fusion method, in particular, outperformed individual and MLR-based approaches, achieving sub-kelvin temperature resolution at all temperatures. These findings demonstrate that Dy3+-doped sodium aluminoborate glass is a promising candidate for reliable, high-precision luminescent thermometry in demanding environments and the power of multiparametric methods MLR and SF over the individual parameters.