Optical Thermometry through Green Upconversion Emissions in Er3+/Yb3+-Codoped CaWO4 Phosphor

Under 980 nm excitation, the temperature-dependent green upconversion emissions from Er3+/Yb3+-codoped CaWO4 phosphor were studied at temperatures from 294 to 923 K. By using the fluorescence intensity ratio technique, the maximum sensitivity for temperature measurement achieved here is approximately 0.0092 K-1, which is much higher than previously reported temperature sensors based on the fluorescence of Er3+ ions in other host materials. With the efficient upconversion fluorescence, the Er3+/Yb3+-codoped CaWO4 is a very promising candidate for optical high-temperature sensors with high sensitivity and good accuracy. (c) 2012 The Japan Society of Applied Physics