The optical quality of Er3+, Yb3+: BaWO4 crystal was grown by Czochralski method. Absorption spectra were measured and energy levels were assigned. According to Judd-Ofelt theory, the spectral strength parameters of E...The optical quality of Er3+, Yb3+: BaWO4 crystal was grown by Czochralski method. Absorption spectra were measured and energy levels were assigned. According to Judd-Ofelt theory, the spectral strength parameters of Er3+ ion were fitted to be Ω2=0.3926×10-20 cm2, Ω4=0.0721×10-20 cm2, Ω6=0.0028×10-20 cm2. Emission peaks centered at around 523, 544 and 670 nm were observed under 334 nm He-Cd laser excitation and emission peaks centered at 1001 and 1534 nm were detected under 976 nm laser excitation. Strong green emission was also observed when the crystal was pumped with 808 nm and 976 nm laser. The mechanisms of frequency upconversion and sensitization were analyzed.展开更多
The Er3+/Yb3+co-doped transparent oxyfluoride glass-ceramics containing CaF2nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy(TEM) images showed that CaF2nano-crystals o...The Er3+/Yb3+co-doped transparent oxyfluoride glass-ceramics containing CaF2nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy(TEM) images showed that CaF2nano-crystals of 20–30 nm in diameter precipitated uniformly in the glass matrix. Comparing with the host glass, high efficiency upconversion luminescence of Er3+at 540 nm and 658 nm was observed in the glass ceramics under the excitation of 980 nm. Moreover,the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er3+and Yb3+was convinced and the possible mechanism of Er3+up-conversion was discussed.展开更多
FTIR absorption spectra indicate that H^+can easily enter the crystal structure and form OH^-centers in Er:Yb:YCOB and O-H bonds prefer to lie in the a-c plane.Within our current studied concentration level,crystal sa...FTIR absorption spectra indicate that H^+can easily enter the crystal structure and form OH^-centers in Er:Yb:YCOB and O-H bonds prefer to lie in the a-c plane.Within our current studied concentration level,crystal samples with higher OH-abso rption coefficie nts demonstrate stro nger fluo rescence intensity and longer fluorescence lifetime at 1535 nm.As the stretching vibration energy of OH-group approximately corresponds to the energy gap between the 4 I11/2 and 4 I13/2 levels of Er^3+,and thus,OH^-ions can shorten the fluorescence lifetime of Er^3+-4I11/2 level by the phonon-assisted cross-relaxation process between the Er^3+and OH-ions.Our curre nt results confirm that a certain conte nt of OH ions can enhance the ene rgy transfer process from Yb^3+to Er^3+and subsequently promote fluorescence output in 1.5-1.6μm.展开更多
Optical characteristics and upconversion dynamics of Er3+ in Er3+/Yb3+:LiLa(MoO4)2 crystals were investigated. The absorption spectra, fluorescence spectra and the fluorescence decay curves were analyzed at room tempe...Optical characteristics and upconversion dynamics of Er3+ in Er3+/Yb3+:LiLa(MoO4)2 crystals were investigated. The absorption spectra, fluorescence spectra and the fluorescence decay curves were analyzed at room temperature. The infrared emission at 1538 nm and visible emissions at 520–569 and 640–670 nm, corresponding to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions, were simultaneously observed in Er3+/Yb3+:LiLa(MoO4)2 crystals under 976 nm excitation at room temperature. The maximal emission cross-section near 1530 nm for π-polarization was 0.63×10–20 cm2 and the measured lifetime of 4I13/2 was 4.88 ms. The upconversion process was involved in sequential two-phonon processes, either the energy transfer from Yb3+ ions or by the excited state absorption.展开更多
基金Project supported by the Key Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences
文摘The optical quality of Er3+, Yb3+: BaWO4 crystal was grown by Czochralski method. Absorption spectra were measured and energy levels were assigned. According to Judd-Ofelt theory, the spectral strength parameters of Er3+ ion were fitted to be Ω2=0.3926×10-20 cm2, Ω4=0.0721×10-20 cm2, Ω6=0.0028×10-20 cm2. Emission peaks centered at around 523, 544 and 670 nm were observed under 334 nm He-Cd laser excitation and emission peaks centered at 1001 and 1534 nm were detected under 976 nm laser excitation. Strong green emission was also observed when the crystal was pumped with 808 nm and 976 nm laser. The mechanisms of frequency upconversion and sensitization were analyzed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61265004,51272097,and 11204113)the Nature and Science Fund from Yunnan Province Ministry of Education,China(Grant No.2011C13211708)
文摘The Er3+/Yb3+co-doped transparent oxyfluoride glass-ceramics containing CaF2nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy(TEM) images showed that CaF2nano-crystals of 20–30 nm in diameter precipitated uniformly in the glass matrix. Comparing with the host glass, high efficiency upconversion luminescence of Er3+at 540 nm and 658 nm was observed in the glass ceramics under the excitation of 980 nm. Moreover,the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er3+and Yb3+was convinced and the possible mechanism of Er3+up-conversion was discussed.
基金Project supported by the National Natural Science Foundation of China(11204148,11374170)Major Basic Research Projects of Shandong Natural Science Foundation(ZR2018ZB0650)+4 种基金China Postdoctoral Science Foundation(2015M580573)the Applied Basic Research Programs for Youths of Qingdao(15-9-1-52-JCH)Taishan Scholar Program of Shandong Provincethe Qingdao Postdoctoral Application Research Project(2015127)the Open Projects of State Key Laboratory of Rare-earth Resource Utilization(RERU2016015)
文摘FTIR absorption spectra indicate that H^+can easily enter the crystal structure and form OH^-centers in Er:Yb:YCOB and O-H bonds prefer to lie in the a-c plane.Within our current studied concentration level,crystal samples with higher OH-abso rption coefficie nts demonstrate stro nger fluo rescence intensity and longer fluorescence lifetime at 1535 nm.As the stretching vibration energy of OH-group approximately corresponds to the energy gap between the 4 I11/2 and 4 I13/2 levels of Er^3+,and thus,OH^-ions can shorten the fluorescence lifetime of Er^3+-4I11/2 level by the phonon-assisted cross-relaxation process between the Er^3+and OH-ions.Our curre nt results confirm that a certain conte nt of OH ions can enhance the ene rgy transfer process from Yb^3+to Er^3+and subsequently promote fluorescence output in 1.5-1.6μm.
基金Project supported by the National Natural Science Foundation of China (60808033) Natural Science Foundation of Jiangxi Province (2008GZW0012)
文摘Optical characteristics and upconversion dynamics of Er3+ in Er3+/Yb3+:LiLa(MoO4)2 crystals were investigated. The absorption spectra, fluorescence spectra and the fluorescence decay curves were analyzed at room temperature. The infrared emission at 1538 nm and visible emissions at 520–569 and 640–670 nm, corresponding to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions, were simultaneously observed in Er3+/Yb3+:LiLa(MoO4)2 crystals under 976 nm excitation at room temperature. The maximal emission cross-section near 1530 nm for π-polarization was 0.63×10–20 cm2 and the measured lifetime of 4I13/2 was 4.88 ms. The upconversion process was involved in sequential two-phonon processes, either the energy transfer from Yb3+ ions or by the excited state absorption.
