Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the imp...Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.展开更多
Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-section...Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.展开更多
Na_(5)Y_(9)F_(32) single crystals doped with ~0.8-mol% Ho^(3+),~1-mol% Tm^(3+),and various Er^(3+) ion concentrations were prepared by a modified Bridgman method.The effects of Er^(3+)ion concentration on 2.0-μm emis...Na_(5)Y_(9)F_(32) single crystals doped with ~0.8-mol% Ho^(3+),~1-mol% Tm^(3+),and various Er^(3+) ion concentrations were prepared by a modified Bridgman method.The effects of Er^(3+)ion concentration on 2.0-μm emission excited by an800-nm laser diode were investigated with the help of their spectroscopic properties.The intensity of 2.0-μm emission reached to maximum when the Er^(3+) ion concentration was ~1 mol%.The energy transfer mechanisms between Er^(3+),Ho^(3+),and Tm^(3+) ions were identified from the change of the absorption spectra,the emission spectra,and the measured decay curves.The maximum 2.0-μm emission cross section of the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystal reached 5.26 × 10^(-21) cm^(2).The gain cross section spectra were calculated according to the absorption and emission cross section spectra.The cross section for ~2.0-μm emission became a positive gain once the inversion level of population was reached 30%.The energy transfer efficiency was further increased by 11.81% through the incorporation of Er^(3+) ion into Ho^(3+)/Tm^(3+) system estimated from the measured lifetimes of Ho^(3+)/Tm^(3+)-and Er^(3+)/Ho^(3+)/Tm^(3+)-doped Na_(5)Y_(9)F_(32)single crystals.The present results illustrated that the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystals can be used as promising candidate for 2.0-μm laser.展开更多
基金Project supported bythe Key Laboratory of Rare Earth Chemistry and Physics ,ChangchunInstitute of Applied Chemistry ,Chinese Academy of Sciences (R020202K)
文摘Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.
基金supported by the National Natural Science Foundation of China (Grant 60777030)the Open Foundation of the Key Laboratory of Ningbo City (2007A22010) K.C.Wong Magna Fund in Ningbo University
文摘Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.
基金Project supported by the National Natural Science Foundation of China(Grant No.51772159)the Natural Science Foundation of Zhejiang Province+2 种基金China(Grant No.LZ17E020001)the Natural Science Foundation of Ningbo City(Grant No.202003N4099)K C Wong Magna Fund in Ningbo University。
文摘Na_(5)Y_(9)F_(32) single crystals doped with ~0.8-mol% Ho^(3+),~1-mol% Tm^(3+),and various Er^(3+) ion concentrations were prepared by a modified Bridgman method.The effects of Er^(3+)ion concentration on 2.0-μm emission excited by an800-nm laser diode were investigated with the help of their spectroscopic properties.The intensity of 2.0-μm emission reached to maximum when the Er^(3+) ion concentration was ~1 mol%.The energy transfer mechanisms between Er^(3+),Ho^(3+),and Tm^(3+) ions were identified from the change of the absorption spectra,the emission spectra,and the measured decay curves.The maximum 2.0-μm emission cross section of the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystal reached 5.26 × 10^(-21) cm^(2).The gain cross section spectra were calculated according to the absorption and emission cross section spectra.The cross section for ~2.0-μm emission became a positive gain once the inversion level of population was reached 30%.The energy transfer efficiency was further increased by 11.81% through the incorporation of Er^(3+) ion into Ho^(3+)/Tm^(3+) system estimated from the measured lifetimes of Ho^(3+)/Tm^(3+)-and Er^(3+)/Ho^(3+)/Tm^(3+)-doped Na_(5)Y_(9)F_(32)single crystals.The present results illustrated that the Er^(3+)/Ho^(3+)/Tm^(3+)tri-doped Na_(5)Y_(9)F_(32) single crystals can be used as promising candidate for 2.0-μm laser.
