Point temperature sensor based on green upconversion emission in an Er:ZBLALiP microsphere

Thermal properties and spectroscopic properties of a new kind heavy fluoride glass Er:ZBLALiP microsphere were presented in this paper. Based on the thermalization effects between the upper levels responsible for green fluorescence at 522 and 546 nm in Er:ZBLALiP, we propose a new optical temperature sensing using micrometer-sized spherical cavity. The dependence of green emission intensity ratio (GEIR) on the surrounding temperature from 300 to 100 K was experimentally determined, which allows us to calibrate the sensing function of green intensity ratio versus temperature. Such a point temperature sensor is applicable for a large temperature range from 150 to 850 K with a resolution of the order of 1 K. (C) 2003 Elsevier B.V. All rights reserved.