Optical temperature sensing using the multiphonon-assisted anti-Stokes-to-Stokes fluorescence intensity ratio.

An optical method based on the multiphonon-assisted anti-Stokes-to-Stokes fluorescence intensity ratio (ASFIR) has been developed for temperature sensing. The ASFIR of YAG:Ce is found to exhibit a near linear and monotonic temperature dependence. Based on these properties, a thermometry using the ASFIR technique has been demonstrated in the range extending from 300 to 800 K with a nearly constant sensitivity of 0.07%  K-1 and a precision of ±2% at 800 K. Also, the conventional dual-Stokes emission bands intensity ratio of YAG:Ce is shown to depend non-monotonically on temperature; thus the suggested ASFIR technique offers an effective method for luminescence thermometry.