共查询到20条相似文献,搜索用时 15 毫秒
1.
Xinshun Wang Jianrong Qiu Juan Song Jian Xu Yang Liao Haiyi Sun Zhizhan Xu 《Optics Communications》2008,281(2):299-302
Near-infrared to ultraviolet upconversion luminescence was observed in the Pr3+:Y2SiO5 crystal with 120 fs, 800 nm infrared laser irradiation. The observed emissions at around 270 nm and 305 nm could be assigned to 5d → 4f transitions of Pr3+ ions. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to simultaneous three-photon absorption induced upconversion luminescence. 相似文献
2.
Optical absorption and photoluminescent properties of Ho3+/Yb3+ co-doped tellurite and zinc tellurite glasses are investigated. The effect of zinc oxide as a modifier on the luminescence properties of above mentioned samples has been explored. Two intense upconversion emission bands centered at 546 (5F4 + 5S2 → 5I8) and 660 nm (5F5 → 5I8) are observed on excitation with 976 nm diode laser. Zinc oxide acts as a quencher for 976 nm excited upconversion emission. The up and downconversion emission spectra are recorded with 532 nm excitation source also. In this case zinc oxide improves the up and downconversion emissions. A large enhancement in upconversion intensity has been observed when Ho3+ ion is co-doped with Yb3+ ion. The dependence of upconversion intensities on excitation power and on temperature has also been studied. The power dependence study shows a quadratic dependence of the fluorescence intensity on the excitation power while a decrement in emission intensity of all the transitions at different rates with increase in temperature is observed in temperature dependence study. The possible mechanisms are also discussed in order to understand the upconversion and energy transfer processes. 相似文献
3.
Hongtao Sun Liyan Zhang Shilong Zhao Junjie Zhang Dongbing He Zhongchao Duan Lili Hu 《Solid State Communications》2005,133(6):357-361
Structural and infrared-to-visible upconversion fluorescence properties of Er3+/Yb3+-codoped oxychloride lead-germanium-bismuth glass have been studied. The Raman spectrum investigation indicates that PbCl2 plays an important role in the formation of glass network, and has an important influence on the upconversion luminescence owing to lower phonon energy. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were observed at room temperature. The quadratic dependence of the 525, 546, and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm excitation. 相似文献
4.
Hongtao Sun Liyan Zhang Junjie Zhang Chunlei Yu Shixun Dai Zhonghong Jiang 《Solid State Communications》2005,133(12):781-784
Infrared-to-visible upconversion fluorescence property of Er3+/Yb3+-codoped novel bismuth-germanium glass under 975 nm LD excitation has been studied. Intense green and red emissions centered at 525, 546 and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were observed at room temperature. The quadratic dependence of the 525, 546 and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs. The structure of the bismuth-germanium glass has been investigated by peak-deconvolution of FT-Raman spectrum, and the structural information was obtained from the peak wavenumbers. This novel bismuth-germanium glass with low maximum phonon energy (∼750 cm−1) can be used as potential host material for upconversion lasers. 相似文献
5.
Efficient upconversion (UC) luminescence is demonstrated in Er3+:Sr2CeO4 powders prepared by combustion synthesis and exposed to near-infrared (∼975 nm) radiation. The UC emission lines observed at ∼530, ∼550 and ∼665 nm correspond, respectively, to 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 4f-4f transitions of Er3+. X-ray powder diffraction data showed that the SrCO3 phase (impurity) is dramatically reduced when Sr2+ is partially substituted by Mg2+ ions. The UC phenomenon was investigated by use of continuous wave and pulsed laser excitation and the UC mechanism was attributed to energy transfer between excited Er3+ ions. 相似文献
6.
Xiang Shen Qiuhua Nie Tiefeng Xu Shixun Dai Xunsi Wang 《Journal of luminescence》2010,130(8):1353-1356
Temperature quenching characteristics of infrared-to-visible frequency upconversion in ytterbium-sensitized erbium-doped tellurite glasses under 970 nm excitation were reported. Intense upconversion emissions around 530, 545 and 657 nm corresponding to the 2H11/2, 4S3/2 and 4F9/2 transitions to the 4I15/2 ground state were observed. The green emission around 530 nm presents continuous increase with increase of temperature. While the emission around 545 nm increases from 20 to 80 K and reaches the largest value around 80 K, then decreases from 80 to 300 K. The dependence of intensity characteristics on temperature was systematically analyzed by rate equations and a simple three-level system. In addition, the temperature dependence on the multiphonon relaxation rates (2H11/2, 4S3/2→4F9/2) fitted with 4 phonons of the 760 cm−1 was presented. 相似文献
7.
Hongtao Sun Junjie Yang Junjie Zhang Zhonghong Jiang 《Solid State Communications》2005,133(12):753-757
Er3+-doped oxychloride germanate glasses have been synthesized by conventional melting and quenching method. Structural and thermal stability properties were obtained based on the Raman spectra and differential thermal analysis, indicating that PbCl2 plays an important role in the formation of glass network and has an important influence on the maximum phonon energy and thermal stability of host glasses. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were observed at room temperature. With increasing PbCl2 content, the intensity of green (525 and 546 nm) emissions increases significantly, while the red (657 nm) emission increases slowly. The results indicate that PbCl2 has more influence on the green emissions than the red emission in oxychloride germanate glasses. The possible upconversion luminescence mechanisms has also been estimated and discussed. 相似文献
8.
The ground state absorption (GSA), photoluminescence (PL) and photoluminescence excitation (PLE) spectra for Er(1.0 at%):YAP and Er(0.5 at%):LSO were measured at room temperature. Based on the GSA spectra, the radiative transition rates and luminescence branch ratios of erbium ions were determined by the Judd-Ofelt (J-O) method. In the range of 1400-1700 nm Er(1.0 at%):YAP has intense absorption at 1509 nm (0.96×10−20 cm2), which is almost two times larger than the peak absorption of Er(0.5 at%):LSO. From the PL and PLE spectra, four intense emission bands around 850 nm (4S3/2→4I13/2), 980 nm (4I11/2→4I15/2), 1230 nm (4S3/2→4I11/2) and 1520 nm (4I13/2→4I15/2) were observed. The stimulated emission cross-sections of the four bands were calculated by the Fuchtbauer-Ladenberg (F-L) equation. The results suggest that Er(1.0 at%):YAP has potential to realize laser oscillation at 858 nm because of the relatively large simulated emission cross-section (1.76×10−20 cm2). The temperature dependences of the PL spectra for the two crystals were also investigated in the range of 290-12 K. The ∼1520 nm emission presents continuous increase with temperature, while the emissions around 850, 1230 and 980 nm firstly increase with temperature, then reach their own largest values at the transition temperatures (about 100 K), and finally decrease with temperature. These results were well interpreted by the temperature dependence of multi-phonon process. 相似文献
9.
Hongtao Sun Liyan Zhang Gang Zhou Junjie Zhang Zhonghong Jiang 《Journal of luminescence》2006,117(2):179-186
Er3+-doped oxyfluoride germanate glasses have been synthesized by the conventional melting and quenching method. The Judd-Ofelt intensity parameters were calculated based on the Judd-Ofelt theory and absorption spectra measurements. With the substitution of PbF2 for PbO, the Ω2 parameter decreases, while the Ω6 parameter increases. These change trends indicate that fluoride anions come to coordinate erbium cations and the covalency of the Er-O bond decreases. Structural and thermal stability properties were obtained by Raman spectra and differential thermal analysis, indicating that PbF2 plays an important role in the formation of glass network and has an important influence on the maximum phonon energy and thermal stability of host glasses. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were simultaneously observed at room temperature. With increasing PbF2 content, the intensity of red (657 nm) emissions increases significantly, while that of the green (525 and 546 nm) emission increases slightly. The results indicate that PbF2 has more influence on the red (657 nm) emission than the green (525 and 546 nm) emissions in oxyfluoride germanate glasses. The possible upconversion luminescence mechanisms have also been estimated and discussed. 相似文献
10.
In this paper we report the upconversion emission for the 4S3/2→4I15/2 Stark components of Er3+ ion-doped fluorozirconate glass at T=2 K. The spectrum shows only seven peaks, one less than expected theoretically, being missing the peak at the wave number 17,996 cm−1 (λ=555 nm). This result is compared with the luminescence for the same transition at the same conditions which exhibits the eight expected lines. Such a discrepancy is attributed to a re-absorption process (ESRA) between the energy levels 4I13/2 and 2H9/2. 相似文献
11.
Feng Song Lin Han Hao Tan Jing Su Jia Yang Jian-guo Tian Guang-yin Zhang Zhen-xiang Cheng 《Optics Communications》2006,259(1):179-186
Using Czochralski (CZ) pulling method, an Er3+/Yb3+-codoped NaY(WO4)2 crystal was prepared. Absorption spectra, emission spectra and excitation spectra of this crystal were measured at room temperature. Some optical parameters, such as intensity parameters, spontaneous emission probabilities and lifetimes, were calculated from absorption spectra with Judd-Ofelt (J-O) theory. Upconversion luminescence excited by a 970 nm diode laser was studied. In this crystal, green upconversion luminescence is particularly intensive. Energy transfer mechanisms that play an important role in upconversion processes were analyzed. Two cross-relaxation processes: 4G11/2 + 4I9/2 → 2H11/2 (or 4S3/2) + 2H11/2 (or 4S3/2), and 4G11/2 + 4I15/2 → 2H11/2 (or 4S3/2) + 2I13/2, which contribute to the intensive green luminescence under 378 nm excitation, were put forward. Background energy transfer 4G11/2(Er3+) + 2F7/2(Yb3+) → 4F9/2(Er3+) + 2F5/2(Yb3+) was also demonstrated. 相似文献
12.
Xujie Li Qiuhua Nie Tiefeng Xu Xianghua Zhang 《Journal of Physics and Chemistry of Solids》2007,68(8):1566-1570
A serials of Ho3+/Yb3+ co-doped tellurite glasses by pumping 970 nm laser diode (LD) were demonstrated to obtain a high efficiency of infrared-to-visible upconversion. Two intense emission bands were observed in Ho3+/Yb3+ co-doped tellurite glasses centered at 549 and 664 nm corresponding to Ho3+: 5S2(5F4)→5I8 and 5F5→5I8 transitions, respectively. The upconversion intensities of red and green emissions in Ho3+/Yb3+ co-doped glasses were enhanced largely when increasing Yb2O3 content. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms had been evaluated by a proper rate equation model. The energy transfer coefficients were estimated by fitting the simulated curves to the measured ones. The obtained three energy transfer coefficients CD2, CD3 and CD4 were CD2=5.0×10−18 cm3/s, CD3=1.5×10−17 cm3/s, CD4=9.0×10−17 cm3/s. 相似文献
13.
The spectroscopic characteristics and fluorescence dynamics for Yb3+/Ho3+:NaY(WO4)2 crystal were investigated. The parameters of oscillator strengths, the spontaneous transition probabilities, the fluorescence branching ratios, the radiative lifetimes and the stimulated emission cross sections have been calculated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The energy transfer efficiency from Yb3+ to Ho3+ was 65.85%. The green emission (530-570 nm) corresponding to (5F4, 5S2)→5I8 transition, red emission (640-670 nm) due to 5F5→5I8 transition and NIR emission (740-770 nm) attributed to (5F4, 5S2)→5I7 transition were observed on 974 nm excitation at room temperature. Under low pump power, the intensity of green light emission is weaker than that of the red light, while under high pump power, the case is on the contrary. The upconversion is based on the two-photon process either the energy transfer from Yb3+ ions or by the excited state absorption. The proposed mechanisms of upconversion emissions were provided. 相似文献
14.
This paper reports on the absorption, visible and near-infrared luminescence properties of Nd3+, Er3+, Er3+/2Yb3+, and Tm3+ doped oxyfluoride aluminosilicate glasses. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4 and Ω6) have been calculated for all the studied ions. Decay lifetime curves were measured for the visible emissions of Er3+ (558 nm, green), and Tm3+ (650 and 795 nm), respectively. The near infrared emission spectrum of Nd3+ doped glass has shown full width at half maximum (FWHM) around 45 nm (for the 4F3/2→4I9/2 transition), 45 nm (for the 4F3/2→4I11/2 transition), and 60 nm (for the 4F3/2→4I13/2 transition), respectively, with 800 nm laser diode (LD) excitation. For Er3+, and Er3+/2Yb3+ co-doped glasses, the characteristic near infrared emission bands were spectrally centered at 1532 and 1544 nm, respectively, with 980 nm laser diode excitation, exhibiting full width at half maximum around 50 and 90 nm for the erbium 4I13/2→4I15/2 transition. The measured maximum decay times of 4I13/2→4I15/2 transition (at wavelength 1532 and 1544 nm) are about 5.280 and 5.719 ms for 1Er3+ and 1Er3+/2Yb3+ (mol%) co-doped glasses, respectively. The maximum stimulated emission cross sections for 4I13/2→4I15/2 transition of Er3+ and Er3+/Yb3+ are 10.81×10−21 and 5.723×10-21 cm2. These glasses with better thermal stability, bright visible emissions and broad near-infrared emissions should have potential applications in broadly tunable laser sources, interesting optical luminescent materials and broadband optical amplification at low-loss telecommunication windows. 相似文献
15.
Xiangfu Wang Siguo Xiao Yanyan Bu Xiaoliang Yang J.W. Ding 《Journal of luminescence》2009,129(3):325-353
A luminescent material β-Na(Y1.5Na0.5)F6 doped with Tm3+ was synthesized by a solid-state reaction method for a steady phosphor of blue upconversion. Under the 671 nm laser excitation, the green emission band of 511 nm due to the 1D2→3H5 transition is obtained for the first time, while the ultraviolet emission band is also observed at 368 nm, associated with the 1D2→3H6 transition. Especially, a wide band of blue emissions is obtained at the wavelength region of 440-490 nm, originated mainly from the 1D2→3F4 (450 nm) and 1G4→3H6 (471-487 nm) transitions, which have potential application in tunable solid-state blue laser of Tm3+. The upconversion mechanism is explored in terms of the energy-level structures of Tm3+ ion and the power dependence of upconverted emission intensity, which is believed to be performed by excited-state absorption. 相似文献
16.
Infrared-to-visible upconversion luminescence has been investigated in Er3+-doped barium-natrium-yttrium-fluoride phosphor (BaxNayYzF2x+y+3z+3m:Erm) with different cation concentrations. Intense upconversion emissions around 530, 550, and 660 nm corresponding to the 2H11/2, 4S3/2, and 4F9/2 transitions, respectively to the 4I15/2 ground state were observed when excited by CW laser radiation at 1550 nm. We adopted the low-temperature combustion synthesis (LCS) method to decrease the phosphor particle size to 40-70 nm in order to couple to the photosensitive surface of CCD. The effect of the amount of carbamide on the particle size and the upconversion luminescence intensity was analyzed. The upconversion luminescence mechanism was studied by the log-log plot of intensity-power. 相似文献
17.
Crystalline structures and infrared-to-visible upconversion luminescence spectra have been investigated in 1 mol% Er3+, 10 mol% Yb3+ and 0-20 mol% Li+ codoped TiO2 [1Er10Yb(0-20)Li:TiO2] nanocrystals. The crystalline structures of 1Er10Yb(0-20)Li:TiO2 were divided into three parts by the addition of Yb3+ and Li+. Both green and red upconversion emissions were observed from the 2H11/2/4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ in Er3+-Yb3+-Li+ codoped TiO2, respectively. The green and red upconversion emissions of 1Er:TiO2 were enhanced significantly by Yb3+ and Li+ codoping, in which the intensities of green and red emissions and the intensity ratio of green to red emissions (Igreen/Ired) were highly dependent on the crystalline structures. The significant enhanced upconversion emissions resulted from the energy migration between Er3+ and Yb3+ as well as the distortion of crystal field symmetry of Er3+ caused by the dissolving of Li+ at lower Li+ codoping concentration and the phase transformation at higher Li+ concentration. It is concluded that codoping with ions of smaller ionic radius like Li+ can efficiently improve the upconversion emissions of Er3+ or other rare-earth ions doped luminsecence materials. 相似文献
18.
用熔融淬冷法制备了掺Er3+的80GeS2-10In2S3-10CsI(mol%)硫卤玻璃样品,测试了样品的热学稳定性、喇曼光谱、吸收光谱以及上转换光谱,分析了Er3+离子在该玻璃中的上转换发光机理.应用Judd-Ofelt理论计算分析了Er3+离子在该样品中的强度参量Ωt(t=2,4,6)、自发辐射跃迁几率A、荧光分支比β以及辐射寿命τrad等光谱参量.在980 nm LD泵浦激发下,首次在该种玻璃中观察到强烈的绿光(526 nm、549 nm),分别对应于2H11/2→4I15/2和4S3/2→4I15/2的跃迁,其中549 nm处绿光较强.549 nm处上转换荧光寿命为0.34 ms,量子效率为69%.同时研究了绿光(526 nm、549 nm)上转换发光强度随泵浦激发功率的变化,其发光曲线拟合斜率分别为1.71和2.03,表明绿光是双光子吸收过程.研究结果表明:掺Er3+的80GeS2-10In2S3-10CsI硫卤玻璃是一种上转换绿光激光器的潜在基质材料. 相似文献
19.
Intense blue upconversion emission at 480 nm has been obtained at room temperature in Tm3+-Nd3+ co-doped Ta2O5 channel waveguides fabricated on a Si substrate, when the sample is excited with an infrared laser at 793 nm. The upconversion mechanism is based on the radiative relaxation of the Nd3+ ions (4F3/2 → 4I11/2) at about 1064 nm followed by the absorption of the emitted photons by Tm3+ ions in the 3H4 excited state. A coefficient of energy transfer rate as high as 3 × 10−16 cm3/s has been deduced using a rate equation analysis, which is the highest reported for Tm-Nd co-doped systems. The confinement of the 1064 nm emitted radiation in the waveguide structure is the main reason of the high energy transfer probability between Nd3+ and Tm3+ ions. 相似文献
20.
Yunfeng Bai 《Optics Communications》2009,282(9):1922-1928
Er/Tm/Yb codoped Y2O3 nanocrystals and Er/Tm/Yb/Li codoped Y2O3 nanocrystals have been synthesized by sol-gel method, bright white light emission has been observed at 976 nm excitation. The blue, green, and red emissions, respectively, arise from the transitions 1G4 → 3H6 of Tm3+, 2H11/2/4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+ ion. Moreover, after doping Li+ ions into Er/Tm/Yb codoped Y2O3 nanocrystals, the white light emission increase greatly. CIE coordinate of Er/Tm/Yb/Li codoped Y2O3 nanocrystals is X = 0.32 and Y = 0.36 at 10 W/cm2 excitation, which is very close to the standard equal energy white light illuminate (X = 0.33, Y = 0.33). 相似文献