Optical temperature sensor based on the Nd 3+ 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 Nd3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the (S-4(3/2), F-4(7/2)), (H-2(9/2), F-4(5/2)),F-4(3/2) -> I-4(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 Nd3+ 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 x 10(-4) K-1 at 640 K, being one of the highest values found in the literature for Nd3+ optical temperature sensors. Finally, the experimental calibrations were compared with the theoretical temperature luminescence response calculated from the Judd-Ofelt theory. (C) 2015 Elsevier B.V. All rights reserved.