Fluorescence intensity ratio method for temperature sensing.

A thermometry method based on the ratio between the valley intensity formed by fluorescence peak overlap and the peak fluorescence intensity has been developed. Excited by a 405 nm laser, the valley to peak ratio (VPR) of the emissions originating from 5D0 to 7F2 Stark sublevels in Eu3+-doped CaWO4 shows a monotonic change with temperature. Spectrum analysis indicates that this monotonic increase is caused by the homogeneous broadening of the spectral lines as the temperature increases. The relative sensitivity S(r) is in the magnitude of 10(-4)  K(-1) in the experimental temperature range of 303-573 K.