Study On Fluorescence Properties Of Terbium Doped Fluorophosphate Glass Used For Ultraviolet Detection And Sensitization

Silicon-based optical sensors are widely used in the detection field due to the advantages of mature technology,stable performance and low cost.However,in ultraviolet region,the increase of absorption intensity of silicon intensifies the compound rate of photo-generated carriers on the surface,which makes their detection response unsatisfactory.An effective solution is using the down-conversion fluorescence effect of rare earth ions to convert ultraviolet light into visible light where silicon-based sensors have higher responsiveness.It is an effective solution to convert ultraviolet light into visible light with higher responsiveness by down-conversion fluorescence effect of rare earth ions.In this paper,a series of Na PO₃-Ba F₂-Al F₃-Ca F₂ system fluorophosphate glass（NBAC glass）was prepared according to the different doping concentration of Tb₄O₇.When the doping concentration reaches 2mol%,crystal disjunction occurs,and its appearance is white and opaque.Then the thermal properties,structural composition and spectral properties of the samples have been tested.The glass transition temperature of 312℃andΔT value of117℃show that the NBAC glass’s advantage of easy processing,good thermal stability.The Judd-Ofelt theoretical model was used to fit and evaluate the J-O strength parameters of each sample,Ω₂ parameters reached 8.08～8.68,show the low symmetry of glass internal ligand field,which was beneficial to the spontaneous radiation intensity of rare earth ions.The other spectral characteristic parameters obtained by further calculation can be well matched with the measured data.The fluorescence excitation spectra at 548nm showed that Tb³⁺had good absorption and emission intensity at 330nm～390nm,and the peak value was at 373nm.In fluorescence emission spectrum,the fluorescence intensity from the ⁵D₃ level is very weak and decreases with the increase of the Tb³⁺doping concentration,which indicates that most of the excited ions transition from the non-radiative ⁵D₃ level to the ⁵D₄level,making the average wavelength move towards the long-wave where the silicon detectors have higher responsiveness.Finally,an optical path was set up to test the enhanced effect of silicon photodiode ultraviolet detection on the Tb-doped glass samples prepared in this paper.The test results showed that fluorescence had a good auxiliary effect on the detector and the detection response rate could be increased by 12%near 370nm.Light Tools software modeling and simulation of test optical path show that there is still room for improvement in fluorescence enhancement,and Tb-doped NBAC glasses show potential to be applied in ultraviolet assisted detection.