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1.
Host-sensitized energy transfer in YVO4 crystals doped with Eu3+ and Er3+ ions was investigated using laser excited time-resolved spectroscopy techniques. The results are consistent with a model in which the energy is transferred by a single step process from self- trapped excitons to activators at low temperatures, and by thermally activated exciton hopping at high temperatures. The rate of the latter process is found to be strongly affected by the trapping step with activator-induced host traps playing an important part in the trapping process. Time-resolved spectroscopy techniques are shown to be expecially useful in separately determining the characteristics of migration and trapping processes in exciton energy transfer. The parameters describing these processes are determined for the systems investigated using both diffusion and generalized random walk theories. 相似文献
2.
Shaozhen Lv Yan Wang Zhaojie Zhu Zhenyu You Jianfu Li Shufang Gao Hongyan Wang Chaoyang Tu 《Applied physics. B, Lasers and optics》2014,116(1):83-89
The polarized absorption, emission spectra and decay time measurements of Pr3+-doped CaYAlO4 single crystal have been performed at room temperature. Based on the Judd–Ofelt theory, the spectroscopic parameters \(\Upomega_{t} (t = 2,4,6)\) , radiative transition probabilities, radiative lifetimes and branching ratios were obtained. The stimulated emission cross-section, fluorescence lifetimes and the quantum efficiency of the promising laser transition were also calculated and compared with other reported crystals. The results show that Pr3+:CaYAlO4 is a promising candidate for visible solid-state laser emission. 相似文献
3.
Zhengping Wang Lianke Sun Shaojun Zhang Xianlin Meng Ruiping Cheng Zongshu Shao 《Optics & Laser Technology》2001,33(1):63
The absorption properties of Nd:YVO4 crystals with various doping levels and lengths are reported. The effective stimulated emission cross-sections of different doping levels are calculated with measured upper-level lifetimes. Our investigation gives good advice on the optimization of LD end-pumped Nd:YVO4 laser. 相似文献
4.
《Journal of luminescence》1987,37(1):1-8
Ion exchange techniques were used to substitute Cr3+ and Rh2+ ions for the sodium ions present in sodium-beta″-alumina single crystals. The optical absorption and fluorescence spectra were obtained and the fluorescence lifetimes measured for both types of samples. In each case the emission consisted of two bands having significantly different decay times. The temperature dependences of the fluorescence intensities and lifetimes were measured for these bands. The results are interpreted in terms of the energy level structures of these ions in different crystal field sites in this host lattice and the diffusion of ions in the conduction plane which changes these sites. 相似文献
5.
R. Lisiecki G. Dominiak-Dzik P. Solarz A. Strz?p W. Ryba-Romanowski T. ?ukasiewicz 《Applied physics. B, Lasers and optics》2010,101(4):791-800
The LuVO4:Er single crystals were grown by the Czochralski technique. The crystal-field split energy levels of Er3+ ion were derived experimentally employing absorption and emission spectra measured at T=10 K. The Judd–Ofelt phenomenological method was used to estimate intensity parameters, radiative lifetimes and branching ratios of luminescence. The excited state dynamics of the LuVO4:Er systems was investigated and experimental lifetimes of emitting levels were measured. The emission cross section of the 4I13/2→4I15/2 transition in the infrared was calculated by the Füchtbauer–Ladenburg method. The gain cross section, estimated for several inverse-population parameters, allowed us to evaluate a potential laser activity of the LuVO4:Er system at 1.6 μm. Also, the potential range of the optical pumping was assessed based on absorption spectra achieved at the room temperature. The optical losses related to the green up-converted emission, encountered under the 978 nm excitation between 300 and 670 K were indicated and discussed. Spectroscopic peculiarities of the Er3+-doped LuVO4 crystal were discussed in relation to optical properties of the YVO4:Er and GdVO4:Er crystals. Taking into account the high quantum efficiency of the 4I13/2 level, and satisfactory absorption and emission features, the LuVO4:Er crystal can be considered as a promising active material for laser operation near 1.6 μm. 相似文献
6.
G. Jia H. Wang X. Lu Z. You J. Li Z. Zhu C. Tu 《Applied physics. B, Lasers and optics》2008,90(3-4):497-502
The polarized absorption and emission spectra of Pr3+ ions in SrWO4 single crystals were investigated at room temperature. The standard and modified Judd–Ofelt theories have been applied to
analyze the polarized absorption spectra to determine the spectroscopic parameters, including the Judd–Ofelt intensity parameters
Ωt (t=2,4,6), radiative transition probabilities, radiative lifetimes and branching ratios. The stimulated emission cross sections
and fluorescence lifetimes of the promising laser level were obtained.
PACS 78.55.Hx; 42.70.Hj; 78.20.-e 相似文献
7.
A sum-frequency yellow-green laser at 554.9 nm is reported by this paper, 946 nm wavelength is obtained from 4F3/2-4I9/2 transition in Nd:YAG and 1342 nm wavelength is obtained from 4F3/2-4I13/2 transition in Nd:YVO4. Using a doubly folded-cavity type-II critical phase matching KTP crystal intra cavity to make 946 nm laser from Nd:YAG and 1342 nm laser from Nd:YVO4 frequency summed, with incident pumped power of 30 W in Nd:YAG and 20 W in Nd:YVO4, TEM00 mode yellow-green laser at 554.9 nm at 1.15 W is obtained and its M2 factor is less than 1.22. The experimental results show that the Nd:YAG and Nd:YVO4 crystals intra-cavity sum-frequency mixing is an effective method for yellow-green laser and it can be applied to other two laser crystals to obtain more all-solid-state lasers with different wavelengths. 相似文献
8.
Fluorescence decay dynamics of main emission manifolds of trivalent praseodymium ions doped in the as-grown and annealed PbWO4 crystals were analyzed in detail. The fluorescence lifetimes of the 3P0 and 1D2 manifolds were obtained from the fluorescence decay curves measured at room temperature. The main mechanism of fluorescence quenching of the 3P0 manifold is the non-radiative relaxation to the defect centers coming into being during crystal growth. The dominant non-radiative relaxation for the 1D2 manifold is the cross-relaxation energy transfer involving the 1G4 and 3F4 manifolds. The Inokuti–Hirayama model was used to analyze the decay dynamics of the 1D2 manifold, and the fluorescence lifetime τ0 of the as-grown and annealed Pr3+:PbWO4 crystals in absence of cross-relaxation energy transfer are derived as 35.2 μs and 37.9 μs, respectively. The annealing treatment can eliminate most defect centers except for those related to the lead vacancies. 相似文献
9.
The effect of Nd3+ concentration on the CW and Q-switched laser performances at 1064 nm from Nd: YVO4 has been studied under diode laser pumping in identical laser configuration. The Nd3+ concentrations used were 1, 2 and 3 at.% in YVO4 crystals. Under the CW operations we have compared the thermal lensing effect, slope efficiencies and also the beam quality
at the fourth-order degeneracy configuration. Q-switching was done with the help of an acousto-optic modulator and we have
compared the pulses obtained from Nd: YVO4 laser with different doping concentration. It was found that the 1 at.%-doped crystal is the best, offering highest optical-to-optical
conversion efficiency (55%), lowest fractional heat load (24%), highest pulse energy (80 μJ) and shortest pulse width (20 ns). It was also found that there was not much difference in performances for 2 and 3 at.%-doped
crystals both in CW and Q-switched configurations. 相似文献
10.
Lasheng Jiang Zhengyang Zhang Yuchan Xiao Qianming Wang 《Journal of luminescence》2012,132(11):2822-2825
Red/green emissive phosphors YVO4: Eu3+ and Y2O3–SiO2: Tb3+ have been synthesized via novel templates direction methods. Photoluminescence studies exhibit the emission intensities as significantly enhanced through pre-encapsulation treatments of designed pyridine amide compounds (YVO4: Eu3+) and 3,4,5-tris(tetradecoxy) benzoic acid (Y2O3–SiO2: Tb3+). The as-prepared vanadate particles turn out to be much less agglomerated based on the dispersion by the organic templates. The obtained composite materials, which demonstrate extraordinary fluorescence properties, could be promising candidates for future optoelectronic devices. 相似文献
11.
YVO4:Eu, and YVO4:Eu/SiO2 nanocrystals (NCs) were prepared by hydrothermal method with citrate as capping ligands. Their morphologies, structures, components, and photoluminescence properties were investigated and presented in this paper. A remarkable fluorescence enhancement up to 2.17 times was observed in colloidal YVO4:Eu/SiO2 NCs, compared to that of colloidal YVO4:Eu NCs. This is mainly attributed to the formation of the outer protecting layers of biocompatible SiO2 shells; which shield the Eu3+ ions effectively from water and thus reduces the deleterious effects of water on the luminescence. Meanwhile, on the basis of laser selective excitation, two kinds of luminescent centers were confirmed in the NCs, namely, inner Eu3+ ions and surface Eu3+ ions. The surface modifications for YVO4:Eu NCs effectively reduced the surface defects and accordingly enhanced the luminescence. The core/shell NCs exhibited long fluorescence lifetime and high photostability under ultraviolet radiation. 相似文献
12.
S. Gołvab P. Solarz G. Dominiak-Dzik T. Lukasiewicz M. Świrkowicz W. Ryba-Romanowski 《Applied physics. B, Lasers and optics》2002,74(3):237-241
Crystals of YVO4:Ho were grown by the Czochralski method. The structure of the low-energy levels of Ho3+ has been estimated experimentally. Intensity parameters, radiative lifetimes, and branching ratios have been calculated in
the framework of the Judd–Ofelt theory. The influence of temperature on luminescence lifetimes has been investigated. The
calculated nonradiative transition rate was compared with the energy-gap law. The potential laser gain for the 5
I
7–5
I
8 transition has been estimated.
Received: 27 June 2001 / Final version: 10 December 2001 / Published online: 7 February 2002 相似文献
13.
We presented a novel orthogonally linearly polarized Nd:YVO4 laser. Two pieces of a-cut grown-together composite YVO4/Nd:YVO4 crystals were placed in the resonant cavity with the c-axis of the two crystals orthogonally. The polarization and power performance of the orthogonally polarized laser were investigated. A 26.2-W orthogonally linearly polarized laser was obtained. The power ratio between the two orthogonally polarized lasers was varied with the pump power caused by the polarized mode coupling. The longitudinal modes competition and the corresponding variable optical beats were also observed from the orthogonally polarized laser. We also adjusted the crystals with their c-axis parallele to each other, and a 40.7-W linearly polarized TEM00 laser was obtained, and the beam quality factors were M2x=1.37 and M2y=1.25. 相似文献
14.
The fluorescence spectra and lifetimes of low lying states of Er3+ in Cs2NaErCl6 single crystals have been investigated at room temperature and at 77 K. The assignments of the 4F-4I and 4I-4I phonon-assisted transitions have been proposed. The fluorescence lifetimes of low lying fluorescing levels have been estimated. 相似文献
15.
E.V. Ivakin A.V. Sukhadolau O.L. Antipov N.V. Kuleshov 《Applied physics. B, Lasers and optics》2007,86(2):315-318
Mechanisms of transient light-induced refractive-index changes in Yb-doped crystals Yb:KYW, Yb:KGW and Yb:YVO4 were studied. Relative amplitudes and lifetimes of the electronic component of phase gratings caused by the polarizability
difference of the excited and unexcited Yb3+ ions and the thermal component arising from thermalization of the pump energy were measured. Polarizability difference values
of the ground 2
F
7/2 and the excited metastable 2
F
5/2 levels at the testing wavelength of 633 nm were determined for all crystals. The thermal diffusivity of the samples was estimated
for selected directions of the thermal gradient. An athermal direction, along which the thermal component of refraction disappears,
was found in Yb:KYW crystal under specific experimental conditions.
PACS 42.70.Hj; 42.65.An; 66.30.Xj 相似文献
16.
A. S. Yasyukevich A. V. Mandrik A. E. Troshin N. V. Kuleshov 《Journal of Applied Spectroscopy》2007,74(1):60-66
In terms of a system of balance equations, we propose a model for describing the operation of lasers based on solid-state
quasi-three-level active media in the cw lasing regime with longitudinal pumping by emission from diode lasers, taking into
account the spatial distribution of the pump and lasing light beams. We model the operation of lasers based on the active
crystals Yb3+:NaLa(MoO4)2 and Yb3+:YVO4, taking into account the proposed spatial distribution function of the intensity and the emission spectrum of the pump.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 55–60, January–February, 2007. 相似文献
17.
Shinki Nakamura Taishi Agata Takayo Ogawa Satoshi Wada Mikio Higuchi 《Optical Review》2013,20(5):390-394
We grew high-quality Yb:LuVO4, Yb:GdVO4, and Yb:YVO4 by the floating zone (FZ) method. It was found by measurement that these crystals had favorable optical properties. A maximum absorption coefficient of 27 cm?1 (FWHM) and a fluorescence bandwidth with a 20 nm (FWHM) were observed for Yb:LuVO4 at a Yb doping level of 4 at. %. Finally, we demonstrated the lasing performances of Yb:LuVO4, Yb:GdVO4, and Yb:YVO4. To our knowledge, this is the first time that a Yb-doped vanadate grown by the FZ method has been used as a laser, and 4 at.% Yb doping of the Yb:LuVO4 and Yb:YVO4 is the highest level of doping at which laser oscillation occurs among the Yb-doped vanadates. 相似文献
18.
M. Nikl K. Nitsch E. Mihkov K. Polk P. Fabeni G. P. Pazzi M. Gurioli S. Santucci R. Phani A. Scacco F. Somma 《Physica E: Low-dimensional Systems and Nanostructures》1999,4(4):323
Luminescence and decay kinetics of the Pb2+ aggregates in CsBr host crystals were measured in the 4–300 K temperature interval and in 10−10–10−3 time scale. Their emission properties are similar to those of CsPbBr3 bulk crystal showing a subnanosecond free exciton emission in the 520–540 nm spectral region and slower trapped exciton emission in the 530–580 nm spectral region. An efficient energy exchange between the free and trapped exciton states is shown by the temperature dependencies of emission spectra. The quantum size effect is demonstrated in the high energy shift and broadening of the absorption and emission spectra and an estimate of the size of the CsPbBr3-like aggregates is provided. Independent evidence of the presence of the CsPbBr3 and Cs4PbBr6 aggregated phases in the CsBr host was obtained by X-ray structural studies. 相似文献
19.
20.
The present paper summarizes results of detailed studies of fluorescence decays and lifetimes of Nd3+, Ce3+ and Cr3+ carried out on a large group of YAC.: Nd, Ce and YAC.: Nd, Ce, Cr single crystals. The average and local lifetimes (mainly for4F3/2 state of Nd3+) of these ions are given and an influence of various processes (energy transfers, cross-relaxation, nonequivalent centres etc.) on their decays are qualitatively discussed.The authors are grateful to J. Kvapil of Monokrystaly Turnov for supplying them with the samples and for many fruitful discussions. 相似文献