Optical thermometry based on upconverted luminescence in transparent glass ceramics containing NaYF4:Yb3+/Er3+ nanocrystals

Yb3+/Er3+ co-doped transparent oxyfluoride glass ceramics (GC) have been successfully fabricated and characterized for the purpose of optical thermometry by measuring the green upconverted fluorescence intensity ratio (FIR) between the two thermally coupled levels (2H11/2 and 4S3/2). The green upconverted emissions in the GC are enhanced by 15 times compared to that of the precursor glass. The dependence of the FIR on temperature ranging from 298 K to 693 K is well fitted with an exponential function by using an effective energy difference of 775 cm−1. Owing to its low phonon energy and high thermal stability, an improved measurement accuracy and widened operating temperature range can be achieved with the GC sample, suggesting that transparent glass ceramics containing NaYF4:Yb3+/Er3+ nanocrystals are promising for application as optical-fiber temperature sensors.