Temperature characteristics of green upconversion fluorescence of Er³⁺-doped SrGdGa₃O₇ crystal

Temperature characteristics of 980-nm-upconverted green 530 and 550 nm fluorescence of Er³⁺-doped SrGdGa₃O₇ single crystal have been studied for temperature sensing purposes. To achieve that, a simple experimental setup has been developed that consists of a 980 nm laser diode, two interference filters, two Si-photocells and two multimeters, while without use of monochromator or focusing lens for fluorescence collection. The study shows that the Er³⁺-doped SrGdGa₃O₇ crystal displays strong green emission intensity (hence good signal-to-noise ratio) and high temperature sensitivity of fluorescence intensity ratio of the 530 and 550 nm emissions, which is (5.6–104.0) × 10⁻³ K⁻¹ in the considered temperature range 100–430 K, depending on the temperature. In addition, the experiments were repeated using a spectrometer and consistent results of temperature characteristics were obtained. Present study shows that the Er³⁺-doped SrGdGa₃O₇ crystal is a promising host material for optical temperature sensing.