Optical characterization of Er³⁺-doped zinc fluorophosphate glasses for optical temperature sensors
2013
Vijaya, N. | Babu, P. | Venkatramu, V. | Jayasankar, C.K. | León-Luis, S.F. | Rodríguez-Mendoza, U.R. | Martín, I.R. | Lavín, V.
Trivalent erbium doped zinc fluorophosphate glasses have been synthesized and their luminescence properties in the green visible range have been investigated as a function of temperature. The Judd–Ofelt theory has been used to predict the transition probabilities, branching ratios and lifetimes for the various excited states of Er³⁺ ions in 0.5mol% of Er₂O₃-doped glass. The effect of Er³⁺ concentration on temperature dependent luminescence has been studied for the wide temperature range from room temperature up to 773K. The fluorescence intensity ratio of the green emissions associated to the two transitions from the thermally coupled ²H₁₁/₂ and ⁴S₃/₂ levels to the ⁴I₁₅/₂ level of Er³⁺ ion has been studied as a function of temperature, and in turn used to determine the thermal sensitivity and relative thermal sensitivity of the glasses. In the present study, the maximum value for the thermal sensitivity of 79×10⁻⁴K⁻¹ at 630K has been obtained for the lowest (0.01mol%) concentration of Er₂O₃-doped glass, one of the highest sensitivity found in the literature and quite close to the theoretical sensitivity calculated from the Judd–Ofelt theory. The results reveal that the zinc fluorophosphate glass having relatively low concentration of Er³⁺ ions can be useful as an optical temperature sensor due to their high sensitivity and the absence of radiative energy transfer processes.
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