Germanotellurite glasses doped with ytterbium and neodymium - Their spectroscopic properties and thermometric capability

Highlights: • Considerable cross-section and line bandwidth of optical gain in GTSN: Yb. • Very efficient Nd to Yb energy transfer. • Nd/Yb transfer-based luminescent thermometry model. • High applicability of novel GTSN: Nd, Yb glass in laser systems. Germanotellurite glasses doped with Yb and co-doped with Nd and Yb were produced using the melt-quenching method. Their spectroscopic properties were analyzed at 300 K and at elevated temperatures up to 725 K in terms of their luminescent qualities and application potential in luminescence thermometry. The Nd–Yb transfer dynamics were discussed. Owing to the efficient energy transfer from Nd to Yb ions, a temperature sensing model based on the intensity between emission bands from ⁴F_5/2 (Nd) and ²F_5/2 (Yb) levels was established, reaching around 0.7%/K of relative sensitivity. Straight after, the model was successfully tested in practical spectroscopy lab conditions to estimate the temperature increase resulting from high power laser diode excitation. Glass spectroscopic features, in conjunction with an intrinsic method for fast and contactless temperature readout, make GTSN: Nd, Yb a promising material especially for optical temperature sensors.