A portable all-fiber thermometer based on the fluorescence intensity ratio (FIR) technique in rare earth doped TeO2–WO3–La2O3–Na2O glass
Abstract
A portable all-fiber thermometer based on the FIR technique in Er3+/Yb3+ co-doped TeO2–WO3–La2O3–Na2O (TWLN) glasses was designed and its temperature sensing performance in the temperature range of 293–569 K was determined in detail. The high glass transition temperature (Tg = 439 °C) of TWLN glass contributes to broadening the range of temperature measurement. The spectroscopic analysis of Eu3+ ions and Judd–Ofelt analysis of Er3+ ions reveal that the rare earth ions are situated in a low symmetry environment in TWLN glass, which suggests that a large FIR change and high temperature sensitivity are expected. Intense green upconversion emission in Er3+/Yb3+ co-doped TWLN glass fiber was easily observed under 980 nm excitation at a low pumping power (1.4 mW). The maximum temperature sensitivity of the portable all-fiber thermometer reached 86.7 × 10−4 K−1 at 553 K. Experimental results showed that the absolute errors were around ±1 K within the temperature range from 285 to 563 K.