Experimental Study Of Temperature Sensor Based On Erbium Ion Doped Gallium Gallate Crystal

In recent years,the optical thermometer based on the fluorescence intensity ratio?FIR?shows great application potential in the field of industrial,biomedical and scientific research.The FIR-thermometer is based on the ratio of the fluorescence intensity of two temperature-dependent emissions from two closely thermo-coupled energy levels.It can reduce the influence of different factors,such as the pump source,environment fluctuation and the collection detector.Moreover,it could achieve highly efficient sensing performance.The excellent temperature performances are not only related to the type of rare earth ions,but also the choice of matrix material and pump light source.In this work,we select Er³⁺-doped gallium gallate crystals as the host materials and the 384nm LED as the pump light source,and perform a systematic research on sensing performance.The optical temperature sensor based on Er:Gd₃Ga₅O₁₂2 crystal under the pumping of 980nm LD is studied.The green fluorescence of 530nm and 550nm are collected by photocells.And we obtain the fitting expression of FIR value varying with temperature?300K-383K?at semi-logarithmic scale.Then,the temperature parameters including signal-to-noise ratio,relative sensitivity and thermal resolution are characterized.The relative sensitivity value is 1.08×10^-2K^-1 at physiological temperature.The measurement error fluctuates between-1.2K and 1.8K.And the signal-to-noise ratio shows very large.In addition,the experiments are repeated using a spectrometer to verify the reliability of photocells.It is the first time to apply the gallate crystal Gd₃Ga₅O₁₂ in temperature sensing field.Moreover,the crystal has been proven to have a good application prospect in temperature sensing.The temperature sensing performances based on Er:SrGdGa₃O₇ crystal using the pumping source of 980nm LD are also studied.The temperature parameters such as signal-to-noise ratio,relative sensitivity and thermal resolution are characterized by the method of photocells.Moreover,the characterization of performances was repeated characterized with a spectrometer.It is the first time to apply the SrGdGa₃O₇crystal in temperature sensing field.More importantly,the crystal exhibits great potential in temperature sensing.The temperature sensing performances based on Er:SrGdGa₃O₇ crystal using down-conversion-luminescence pumping sources of 488nm xenon lamp and 384nm LED are studied.After collecting the absorption spectra of Er³⁺-doped SrGdGa₃O₇crystal,the 488nm xenon lamp and 384nm LED are selected as the pumping source of temperature sensor according to the absorption peak positions.Then,the up-conversion and down-conversion luminescence mechanisms of the Er³⁺-doped SrGdGa₃O₇ crystal are analyzed comparatively.Considering the factors of temperature sensing characteristics,cost,and structural compactness,we present the great advantages of 384nm LED light source in temperature sensor system.