Temperature characteristics of the green up-conversion fluorescence of Er³⁺-doped Gd₃Ga₅O₁₂ single crystal for temperature sensing

Temperature characteristics of 980-nm-upconverted green 530 and 550 nm emissions of Er³⁺-doped Gd₃Ga₅O₁₂ single crystal have been studied for temperature sensing purposes. To this aim, a simple experimental setup has been developed that consists of a laser diode, two interference filters and two Si photocells, and does not use a monochromator or focusing lens for fluorescence collection. The study shows that the Er³⁺-doped Gd₃Ga₅O₁₂ crystal displays stronger green upconversion fluorescence intensity (hence better signal-to-noise ratio) and higher temperature sensitivity of the fluorescence intensity ratio of the 530 to 550 nm emissions, which is (6.1-113.5)×10^-3 K^-1 in the 100-430 K temperature range. These results indicate that the Er³⁺-doped Gd₃Ga₅O₁₂ crystal is a promising material for optical temperature sensing. KEYWORDS: Er:Gd₃Ga₅O₁₂ Single Crystal, Green Upconversion, Fluorescence Intensity Ratio (FIR), Temperature Characteristics, Optical Temperature Sensing.