共查询到20条相似文献,搜索用时 31 毫秒
1.
《Journal of Non》2007,353(18-21):1748-1754
Efficient infrared-to-visible conversion is reported in thin film nano-composites, with composition 90% SiO2–10% TiO2, fabricated by a spin-coating sol–gel route and co-doped with Er3+ Yb3+ and with Nd3+:Yb3+ ions. The conversion process is observed under 808 nm laser diode excitation and results in the generation of green (526 and 550 nm) and red (650 nm) emissions: from the former, and blue (478 nm) and green (513 and 580 nm) emissions from the latter. The main mechanism that allows for up-conversion is ascribed to energy transfer among Er3+ and Yb3+ ions in their excited states. Up-conversion efficiency for red emission predominates in samples doped with Er3+:Yb3. The results illustrate the large potential of this class of materials for photonic applications in optoelectronics devices. 相似文献
2.
The preparation process and upconversion luminescence properties of the Yb3+ and Tm3+ co-doped glass ceramic containing SrF2 nanocrystals were investigated. In the glass ceramic, the SrF2 nanocrystals were embedded uniformly in the glass matrix. The Yb3+ and Tm3+ ions could be enriched into the precipitated SrF2 nanocrystalline phase, which provide much lower phonon energy than the glass matrix. The glass ceramic exhibited much stronger upconversion luminescence from ultraviolet to visible than the precursor glass. The upconversion luminescence mechanisms were mainly attributed to Yb3+-Yb3+ cooperative upconversion, Yb3+-Tm3+ energy transfer and Tm3+-Tm3+ cross relaxation. 相似文献
3.
A Er3+ and Yb3+ co-doped transparent oxyfluoride glass ceramic containing BaF2 nanocrystals has been prepared. The formation of BaF2 nanocrystals in the glass ceramic was confirmed by X-ray diffraction. Intense upconversion luminescence in the Er3+ and Yb3+ co-doped glass ceramic could be observed. Stark splitting of the Er3+ upconversion luminescence peaks in the glass ceramic indicated that Er3+ and Yb3+ had been incorporated into the BaF2 nanocrystals. Near infrared luminescence decay curves showed that the Er3+ and Yb3+ co-doped glass ceramic had higher luminescence efficiency than the precursor glass. 相似文献
4.
Yb-doped aluminoborosilicate glasses were irradiated with 2.3 MeV electron and gamma rays at different doses ranging between 104 and 2.6 × 109 Gy and the local structure around the Yb3+ ions has been studied using a combination of NMR, EPR and photoluminescence spectroscopic techniques. The spectroscopic results indicate the presence of two distinct Yb3+ sites in these glasses and their relative fractions depend on both the Yb concentration and the irradiation dose. These two sites can be attributed to Yb3+ ions with and without Yb next-nearest neighbors. The evolution of the shape of the 7F5/2 → 7F7/2 infrared emission band under irradiation is explained by a preferential reduction of the Yb3+ ions with Yb next-nearest neighbors at high integrated doses (> 108 Gy). This interpretation is supported by a strong decrease of the visible cooperative luminescence under irradiation due to the reduction into the Yb pairs. In other terms, it shows an interesting effect of ionizing irradiation on the Yb clusters. A low intensity emission band appears in irradiated samples at 390 nm that can be attributed to Yb2+. Finally, the decrease of the Yb3+ fluorescence lifetime observed under irradiation appears to be primarily due to electronic interaction of these ions with Non-Bridging Oxygen Hole Centre defects created by the ionizing radiation. 相似文献
5.
Luminescence characteristics of Yb3+, La3+ codoped yttrium oxide nanopowders were investigated. The grain size and the crystallinity of (Yb0.05Y0.90La0.05)2O3 nanopowders increase with the increase of calcination temperature. The average grain size of the nanopowders calcined at 1100 °C is 66 nm and its cooperative up-conversion luminescence centered at 498 nm was detected due to nanometer size effect and perfect crystallinity. However, the cooperative up-conversion luminescence of (Yb0.05Y0.90La0.05)2O3 transparent ceramics was not detected. 相似文献
6.
《Journal of Non》2006,352(23-25):2585-2588
We report on the fabrication and spectroscopic characterization of highly photo-refractive Er3+/Yb3+ coactivated silica–germania slab waveguides, single mode at 1550 nm, deposited by radio-frequency-magnetron-sputtering technique. Details of the sputtering procedure are reported. The structural properties of the films were investigated by Raman spectroscopy. Propagation losses of guided modes were measured at 633 nm and 1320 nm. The emission of the 4I13/2 → 4I15/2 transition of the Er3+ ion was analyzed upon excitation of the TE0 mode at 514 and 981 nm. Back energy transfer from Er3+ to Yb3+ was observed by measurement of Yb3+ emission upon Er3+ excitation at 514.5 nm. Photoluminescence excitation spectroscopy was used to obtain information about the Yb3+ to Er3+ energy transfer process. 相似文献
7.
The oxyfluoride glass ceramics are important up-conversion luminescent materials. Er3+/Yb3+-codoped transparent oxyfluoride glasses were prepared by melt-quenching and subsequently heat-treated at different times and temperatures, and the crystallization process of fluoride nanocrystals from the glass was investigated. X-ray diffraction (XRD) and fluorescence spectra investigations reveal that fluoride nanocrystals are distributed homogeneously among the glassy matrix for the sample doped with Er3+/Yb3+. The crystallization process indicates that heat-treatment temperature influences the size of fluoride nanocrystals, while heat-treatment time influences their concentration. Moreover, the red emission intensities increase due to the incorporation of Er3+/Yb3+ into the fluoride nanocrystals under different heat-treatment methods, which are studied by fluorescence spectra. 相似文献
8.
In this paper we investigate the energy transfer processes in Tm3+/Er3+ doped telluride glass pumped at the commercial diode laser pump wavelength ∼800 nm. Tailoring the rare-earths content in the glass matrix, seven main energy transfer channels within the doping range considered were identified. A 6-fold enhancement of the Er3+ visible frequency upconversion fluorescence at ∼660 nm is observed due to the inclusion of Tm3+ ions. This is evidence of the relevant contribution of the route Er1(4I11/2) + Er2(4I13/2) → Er1(4I15/2) + Er2(4F9/2) to the process. Energy migration among pumped 4I9/2 level reducing the efficiency of the upconversion emission rate (3H11/2, 4S3/2, and 4F9/2) is observed for Er3+ above 1.5 wt%. The rate equations regarding the observed energy transfer routes are determined and a qualitative analysis of the observed processes is reported. 相似文献
9.
The upconversion luminescence and near infrared luminescence of the Er3+ ions in transparent oxyfluoride glass-ceramics containing CaF2 nanocrystals have been investigated. The formation of CaF2 nanocrystals in the glass-ceramics was confirmed by XRD. The oscillator strengths for several transitions of the Er3+ ions in the glass and glass-ceramics have been obtained and then the Judd-Ofelt parameters were calculated. The split near infrared emission peaks of the Er3+ ions in the glass-ceramics can be observed because the Er3+ ions have been incorporated into crystalline environment of the CaF2 nanocrystals. The upconversion luminescence intensity of Er3+ ions in the glass-ceramics increased significantly with increasing heat treated time. The transition mechanism of the upconversion luminescence has been ascribed to a two-photon absorption process. 相似文献
10.
In this work, we have prepared a sol-gel derived hybrid material directly doped with Er1.4Yb0.6(Benzoate)6(Phen)2 (Phen = 1,10-phenanthroline) complex, which was reported with intramolecular Yb-Er energy-transfer process in our previous work. The infrared (IR) spectra of the pure complex and hybrid gel material were investigated. The NIR photoluminescence (PL) spectrum of hybrid gel material shows strong characteristic emission of Er3+ with broad full width at half-maximum (FWHM) of 70 nm. Judd-Ofelt theory was used in order to analyze the optical properties of Er3+ ions in the hybrid gel material. 相似文献
11.
Yunfei Qu Rui Wang Liang Liu Jinchao Sun Lili Xing Ye Tao Xiaohong Wu 《Crystal Research and Technology》2013,48(12):1031-1038
The effect of Yb3+ concentration on the fluorescence of 12CaO·7 Al2O3:Ho3+/Yb3+ polycrystals is investigated. The Raman spectra of pure C12A7 under 633‐nm excitation show that the highest photon energy is 787.267 cm−1, which is not much bigger than general fluorides, so it can realize high efficiency upconversion. The upconversion emission spectra suggest that the green upconversion emission centered at 548 nm and the red upconversion emission at 662 nm correspond to the 5F4/5S2→5I8 and 5F5→5I8 transition of Ho3+ ions, respectively. The intensity of the upconversion luminescence and the ratio of red to green are changed with Yb3+ ion concentration. The pump dependence and luminescence decay dynamics spectra show the green and red upconversion emissions are populated by a two‐photon process, and the upconversion mechanisms are analyzed. The relative luminous efficiencies of green and red emissions are 2.035% and 0.7%, respectively. The normalized efficiency obtained for green emission of Ho3+ at RT when the sample is excited by 980‐nm light with an absorbed intensity of 7.5 W/cm2 is 0.27 cm2/W. This result is comparable to the values obtained in YF3 for the Yb3+, Er3+ green emission. The C12A7 with upconversion red and green light will be a promising luminous material. 相似文献
12.
Jiazhong Zhang Haiping Xia Yongzhang Jiang Shuo Yang Xuemei Gu Jianli Zhang Haochuan Jiang Baojiu Chen 《Crystal Research and Technology》2015,50(7):574-579
Downconversion (DC) luminescence with emission at about 1000 nm under excitation of 448‐nm light in Ho3+/Yb3+ codoped α‐NaYF4 single crystal is realized. The crystal was grown by the Bridgman method using KF as an assisting flux in a NaF‐YF3 system. The energy‐transfer process and quantum cutting (QC) mechanisms are presented through the analysis of the spectra. The energy‐transfer processes of first‐ and second‐order cooperative DC are responsible for the increase of the emission intensity at 1000 nm, and it is the first‐order cooperative DC that is dominant for the DC process. When the Ho3+ concentration is fixed at about 0.8 mol%, the optimal concentration for ∼1000 nm emission is 3.02 mol% Yb3+ in the current research. The energy‐transfer efficiency and the total quantum efficiency are analyzed through the luminescence decay curves. The maximum quantum cutting efficiency approaches to 184.4% in α‐NaYF4 single crystals of 0.799 mol% Ho3+ and 15.15 mol% Yb3+. However, the emission intensity at 1000 nm decreases while the energy‐transfer efficiency from Ho3+ to Yb3+ increases, which may result from the fluorescence quenching between Ho3+ and Yb3+ ions, Yb3+ and Yb3+ ions. 相似文献
13.
《Journal of Non》2006,352(9-20):1192-1195
We present a study of the photoluminescence (PL) of structures of Si nanocrystals (nc-Si) in erbium-doped amorphous silicon dioxide. It is shown that the energy of excitons confined in nc-Si of 2–5 nm sizes is efficiently transferred to Er3+ ions in surrounding SiO2 and a strong PL line at 1.5 μm appears. At high excitation intensity the population inversion of Er3+ ion states is achieved. These results demonstrate good perspectives of Er-doped nc-Si/SiO2 structures for possible applications in Si-based optical amplifiers and lasers. 相似文献
14.
Yannan Qian Rui Wang Lili Xing Yanling Xu Chunhui Yang Xinrong Liu 《Crystal Research and Technology》2011,46(11):1137-1142
Congruent Er3+(3 mol%):LiNbO3 crystals codoped with ZnO (X mol %, X=0, 3, 6 and 7) were grown by the Czochralski technique. The Er contents in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP‐AES). Under 800 nm excitation, the upconversion emission spectra reveal an enhancement of the green emission with respect to the red emission when the Zn2+ ions are introduced into Er:LiNbO3 crystal. The effect of Zn2+ ions concentration on the intensity ratio of the green to red emission has been investigated. Two cross‐relaxation processes (2H11/2 + 4I13/2 → 4I11/2 + 4F9/2 and 4F7/2 + 4I11/2 → 4F9/2 + 4F9/2) are involved in populating the 4F9/2 state, which bypass the green‐emitting states. The OH‐ absorption spectra indicate that the Zn2+ codoping leads to a decreased concentration of Er3+ cluster sites contributing to the enhancement of the green emission. The studies on UV‐vis absorption spectra show that the heavily codoped with Zn2+ results in the reformation of the Er3+ cluster sites in Er:LiNbO3. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
《Journal of Non》2006,352(32-35):3636-3641
Sodium phosphoniobate glasses with the composition (mol%) 75NaPO3–25Nb2O5 and containing 2 mol% Yb3+ and x mol% Er3+ (0.01 ⩽ x ⩽ 2) were prepared using the conventional melting/casting process. Er3+ emission at 1.5 μm and infrared-to-visible upconversion emission, upon excitation at 976 nm, are evaluated as a function of the Er3+ concentration. For the lowest Er3+ content, 1.5 μm emission quantum efficiency was 90%. Increasing the Er3+ concentration up to 2 mol%, the emission quantum efficiency was observed to decrease to 37% due to concentration quenching. The green and red upconversion emission intensity ratio was studied as a function of Yb3+ co-doping and the Er3+–Er3+ energy transfer processes. 相似文献
16.
F.A. Bomfim J.R. Martinelli L.R.P. Kassab N.U. Wetter J.J. Neto 《Journal of Non》2008,354(42-44):4755-4759
The effect of Yb3+ concentration on the frequency upconversion (UPC) of Er3+ in PbO–GeO2–Ga2O3 glasses is reported for the first time. Samples were prepared with 0.5 wt% of Er2O3 and different concentrations of Yb2O3 (1.0–5.0 wt%). The green (523 and 545 nm) and red (657 nm) emissions are observed under 980 nm diode laser excitation. The dependence of the frequency UPC emission intensity upon the excitation power was examined and the UPC mechanisms are discussed. An interesting characteristic of these glasses is the increase of the ratio of red to green emission, through an increase of the Yb3+ concentration due to an efficient energy transfer from Yb3+ to Er3+. 相似文献
17.
Glasses of the 25Ln2O3-25B2O3-50GeO2 composition (mol%) where Ln = (1 − x − y) La, xEr, yYb, with an addition of Al2O3 have been obtained and their luminescent characteristics examined. Probabilities of spontaneous emission, peak sections of the induced radiation and quantum yields of luminescence corresponding to the 2F5/2 → 2F7/2 transition of Yb3+ ions and the 4I13/2 → 4I15/2 transition of Er3+ ions have been defined. Quantum yield of Yb3+ luminescence for glasses with low Yb2O3 concentration reaches values closed to 100%. The luminescence spectrum of Er3+ ions exhibits a broad peak at about 1530 nm with effective width more than 80 nm when excited by irradiation at λ = 977 nm. Spontaneous emission probability and peak stimulated radiation section for Er3+ luminescence band 4I13/2 → 4I15/2 were determined to be equal to 175 s−1 and 4.9 × 10−21 cm2 respectively. Effective quenching of both rare-earth activators by oscillations with ν ≈ 2630 and 2270 cm−1 was found. These oscillators, most likely, represent OH-groups connected by a hydrogen bond with non-bridging oxygen atoms in the borogermanate matrix. 相似文献
18.
This study was explored in series of the optical, thermal, and structure properties based on 60P2O5-10Al2O3-30ZnO (PAZ) glasses system that doped with varied rare-earth (RE) elements Yb2O3/Er2O3. The glass transition temperature, softening temperature and chemical durability were increased with RE-doping concentrations increasing, whereas thermal expansion coefficient was decreased. In the optical properties, the absorption and emission intensities also increase with RE-doping concentrations increasing, When Er2O3 and Yb2O3 concentrations are over than 3 mol% in the Er3+-doped PAZ system and Yb3+-doped concentration is over than 3 mol% for Er3+/Yb3+-codoped PAZ system, the emission intensity significantly decreases presumably due to concentration quenching, formation of the ions clustering, and OH− groups in the glasses network. It is suggested that the maximum emission cross-section (σe) is 7.64 × 10− 21 cm2 at 1535 nm is observed for 3 mol% Er3+-doped PAZ glasses. Moreover, the maximum σe × full-width-at-half-maximum is 327.8 for 5 mol% Er3+-doped PAZ glasses. 相似文献
19.
Kefeng Li Sijun Fan Lei Zhang Qiang Zhang Junjie Zhang Lili Hu 《Journal of Non》2011,357(11-13):2417-2420
Tm3+-doped and Tm3+/Yb3+-codoped TeO2–ZnO–Bi2O3 (TZB) glasses are prepared by melt-quenching method. The Judd-Ofelt intensity parameters (Ωt t = 2, 4, 6), radiative transition rate, and radiative lifetime of Tm3+ are calculated based on the absorption spectra. The 1.8 μm emission of the samples is investigated under 980 nm laser excitation. The absorption, emission cross-sections, and gain coefficient of Tm3+:3F4 → 3H6 are calculated. The energy transfer processes of Yb3+–Yb3+ and Yb3+–Tm3+ are analyzed, the results show that the Yb3+ ions can transfer their energy to Tm3+ ions with large energy transfer coefficient, and a maximum efficiency of 79%. 相似文献
20.
A. Chiasera C. Armellini S.N.B. Bhaktha A. Chiappini Y. Jestin M. Ferrari E. Moser A. Coppa V. Foglietti P.T. Huy K. Tran Ngoc G. Nunzi Conti S. Pelli G.C. Righini G. Speranza 《Journal of Non》2009,355(18-21):1176-1179
95.8SiO2–4.2HfO2 planar waveguide activated by 0.2 mol% Er and 0.2 mol% Yb was fabricated by multi-target rf-sputtering technique. The optical parameters were measured by an m-line apparatus operating at 543.5, 632.8, 1319 and 1542 nm. The waveguide compositions were investigated by energy dispersive spectroscopy. The waveguide exhibits a single propagation mode at 1.3 and 1.5 μm with an attenuation coefficient of 0.2 dB/cm at 1.5 μm. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 42 nm bandwidth was observed upon TE0 mode excitation at 980 and 514.5 nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er3+ ions by co-doping with Yb3+ ions. Channel waveguide in rib configuration were fabricated by wet etching process in the active film. 相似文献