Optical temperature sensor based on the Nd3+ infrared thermalized emissions in a fluorotellurite glass

The temperature dependence of the infrared luminescence of a fluorotellurite glass doped with 0.01 and 2.5 mol% of Nd 3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the ( 4 S 3/2 , 4 F 7/2 ), ( 2 H 9/2 , 4 F 5/2 ), 4 F 3/2 → 4 I 9/2 transitions were measured in a wide range of temperatures from 300 upto 650 K. The changes in the emission profiles were calibrated by means of the fluorescence intensity ratio technique. The calibrations showed a strong dependence on the Nd 3+ ions concentration, having the low-doped concentrated sample the best response to changes of temperature. The maximum value obtained for the thermal sensibility is 17×10 −4  K −1 at 640 K, being one of the highest values found in the literature for Nd 3+ optical temperature sensors. Finally, the experimental calibrations were compared with the theoretical temperature luminescence response calculated from the Judd–Ofelt theory.