Crystal Field Regulation And Tunable Mid-infrared Luminescence Mechanism Of Rare Earth Perovskite Fluoride Glass

In recent years,the mid-infrared（MIR）source has become important for a wide range of applications in sensing,spectroscopy,imaging and communications.Due to the unique intra-4f shell transition,rare earth ions doped laser material has been widely used in infrared light-emitting devices.Despite recent advances with mid-infrared gain of rare earth ions,the lack of a tunable mid-infrared luminescence mechanism remains a significant technological challenge.Here,an efficient mechanism for tuning the local crystal field of rare earth ions by modifying the crystal structure of rare earth perovskites is revealed and tunable mid-infrared luminescence of rare earth ions is achieved.A series of CsPb_1-xEr_xBr₃rare earth perovskite fluoride glasses with broad tunable mid-infrared emission have been synthesised by the conventional melt-quenching method.The local crystal field of Er³⁺is tuned by changing the crystal structure of CsPb_1-xEr_xBr₃rare earth perovskite and the FWHM of the mid-infrared emission is tunable from 80 nm to 130 nm.The results indicate that the possible reasons for the broadening of the 2.7μm emission spectra is that the splitting of ⁴I_13/2energy level.The energy level splitting influenced the transition process of⁴I_13/2→⁴I_15/2（1550 nm）and⁴I_11/2→⁴I_13/2（2750 nm）.Tunable mid-infrared luminescence spectra contained from 2600-2900 nm was obtained.A convenient,highly accurate device has also been developed that can be used to measure the CO₂concentration in hydrogen energy.The perovskite glass infrared light source has been well adapted to the characteristic infrared absorption peak of CO₂.The instrument can monitor the CO₂concentration in real time,avoiding the safety risks associated with the use of electronic instruments in hydrogen energy.A series of CsPb_1-xHo_xBr₃rare earth perovskite fluoride glasses with tunable mid-infrared emission have been synthesised by the conventional melt-quenching method.Multi-peak emission of Ho³⁺ions in the near-infrared bands of 1200 nm,1480 nm,1560 nm,1680 nm,and 2060 nm was achieved by combining the infrared luminescence characteristics of Ho³⁺ions with the structural characteristics of perovskite.Ho³⁺ions exhibit bimodal emission at 2880 nm and 2960 nm in the mid-infrared by tuning the crystal structure of CsPb_1-xHo_xBr₃rare earth perovskite to regulate the local crystal field.The ⁵I₆energy level of the Ho³⁺ions is split,which affects the transition process:⁵F₅→⁵I₆（1480 nm）and⁵I₆→⁵I₇（2880 nm）.The 2880nm mid-infrared luminescence of CsPb_1-xHo_xBr₃rare earth perovskite glass infrared light source coincides with the characteristic infrared absorption peak of CO₂.CsPb_1-xHo_xBr₃rare earth perovskite glass infrared light source and can be used to detect the concentration of CO₂in hydrogen energy.A series of CsPb_1-x-yEr_xDy_yBr₃rare earth perovskite fluoride glasses were prepared by melt quenching method and tunable emission in a wide range of 2600nm-3400 nm was realized.Er³⁺ions show mid-infrared emission at 2750 nm,whereas Dy³⁺ions show bimodal emission at 2900 nm and 3050 nm.Dy³⁺ions have different luminescence properties in cubic perovskites and orthorhombic perovskites.The Dy³⁺ions in the orthorhombic perovskite structure exhibit an enhanced luminescence peak at 3050 nm.CsPb_1-x-yEr_xDy_yBr₃perovskite glass has low phonon energy and high stability.The glass can be used in 3μm wide spectral solid state lasers and gas detection.These results are expected to open a wide avenue for a new type of tunable mid-infrared luminescence for a wide range of applications.