The luminescence of Nd3+-doped in NaBi(WO4)2 single crystal was investigated from 10 K to room temperature.The excitation source was a pulsed dye laser in resonance into the(4G5/2+2G(1)7/2) levels of Nd3+ ions.Several...The luminescence of Nd3+-doped in NaBi(WO4)2 single crystal was investigated from 10 K to room temperature.The excitation source was a pulsed dye laser in resonance into the(4G5/2+2G(1)7/2) levels of Nd3+ ions.Several blue emission bands in the up-conversion luminescence spectra corresponded to transitions from 2P1/2 to 4I9/2.Some violet bands corresponding to transitions of 4D3/2→(4I9/2,4I11/2,4I13/2) were also observed.For comparison,the luminescence spectra and decay curves excited by the pulsed 355 nm laser were measured.In order to investigate up-conversion mechanisms,the decay behavior and the dependence of the up-conversion luminescence on laser powers were investigated.The temporal decay behavior of the up-conversion luminescence indicated that the two-photon excited state absorption of the Nd3+ ions was the dominant mechanism in this crystal.展开更多
The up-conversion luminescence tuning of rare-earth ions is an important research topic for understanding luminescence mechanisms and promoting related applications. In this paper, we experimentally study the up-conve...The up-conversion luminescence tuning of rare-earth ions is an important research topic for understanding luminescence mechanisms and promoting related applications. In this paper, we experimentally study the up-conversion luminescence tuning of Er^(3+)-doped ceramic glass excited by the unshaped, V-shaped and cosine-shaped femtosecond laser field with different laser powers. The results show that green and red up-conversion luminescence can be effectively tuned by varying the power or spectral phase of the femtosecond laser field. We further analyze the up-conversion luminescence tuning mechanism by considering different excitation processes, including single-photon absorption(SPA), two-photon absorption(TPA), excited state absorption(ESA), and energy transfer up-conversion(ETU). The relative weight of TPA in the whole excitation process can increase with the increase of the laser power, thereby enhancing the intensity ratio between green and red luminescence(I_(547)/I_(656)). However, the second ETU(ETU2) process can generate red luminescence and reduce the green and red luminescence intensity ratio I_(547)/I_(656), while the third ESA(ESA3) process can produce green luminescence and enhance its control efficiency. Moreover, the up-conversion luminescence tuning mechanism is further validated by observing the up-conversion luminescence intensity, depending on the laser power and the down-conversion luminescence spectrum under the excitation of 400-nm femtosecond laser pulse. These studies can present a clear physical picture that enables us to understand the up-conversion luminescence tuning mechanism in rare-earth ions, and can also provide an opportunity to tune up-conversion luminescence to promote its related applications.展开更多
The surface of an up-conversion luminescence material was modified by overcoating with SiO2, which was syn- thesized from a hydrolysis progress of tetraethoxysilane (TEOS) in alkalescent condition. By analyzing the hy...The surface of an up-conversion luminescence material was modified by overcoating with SiO2, which was syn- thesized from a hydrolysis progress of tetraethoxysilane (TEOS) in alkalescent condition. By analyzing the hydrolyzed mechanism of TEOS, it was found that there was not only physical adsorption but also chemical bonding between the up-conversion material and SiO2. At the same time, some adsorption bands at 1100, 475, 950, and 3500 cm?1 were found by FI-IR, which were the characteristic bands of Si?OH and Si?O?Si. By analyzing the surface elements of the coated material by XPS, it was found that its surface only included Si, O, and C elements, and not F and Y. In the picture of XRD, there was no additional peak after surface modification, suggesting that the silica shell was amorphous. The small peak at 2θ = 23° in the X-ray diffraction pattern of the coated material was caused by the amorphous SiO2 shell, and the TEM image also proved that the surface of the material was successfully modified by overcoating with SiO2. The amount of hydroxyls was then increased on the surface of the material, which made it easy to connect with other active groups.展开更多
A new method was reported for surface modification of an up-conversion luminescence material with hydrosulfide group. The factors that may influence the surface modification,such as reaction time,amount of catalyzer a...A new method was reported for surface modification of an up-conversion luminescence material with hydrosulfide group. The factors that may influence the surface modification,such as reaction time,amount of catalyzer and modifier,and reaction solvent,were investigated. The optimal conditions were that the reaction time,the quantity of the basic catalyzer,the quantity of modifier and the volume of reaction solvent were 40 min,1.0,1.0,and 40 mL,respectively. The results indicated that hydrosulfide group content modified on the surface of up-conversion luminescence material reached to 0.1430 mmol/g,and this modified up-conversion lumi-nescence material could be widely used in the study of structure of protein and the property of microenvironment.展开更多
Up conversion processes for the blue, green and red emissions were found two photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd 3+ →Yb 3+ → Ho 3+ energy transfer. The strong g...Up conversion processes for the blue, green and red emissions were found two photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd 3+ →Yb 3+ → Ho 3+ energy transfer. The strong green emission due to the Ho 3+ : ( 5F 4 , 5S 2) → 5I 8 transitions was observed in Nd 3+ - Ho 3+ co doped ZrF 4 based fluoride glasses under 800 nm excitation. As an attempt to enhance Ho 3+ up conversion luminescences in the Nd 3+ - Ho 3+ co doped ZrF 4 based glasses, Yb 3+ ions were added to the glasses. As a result it was found that, in 800 nm excitation of 60ZrF 4. 30BaF2. (8- x )LaF 3. 1NdF 3. x YbF 3. 1HoF 3 glasses ( x =0 to 7), sensitized up conversion luminescences are observed at around 490 nm (blue), 545 nm (green), and 650 nm (red), which correspond to the Ho 3+ : 5F 3 → 5I 8 , ( 5F 4 , 5S 2) → 5I 8 and 5F 5 → 5I 8 transitions respectively. The intensities of the green and red emissions in a 3 mol % YbF 3 containing glass were about 50 times stronger than those glasses without YbF 3. This is based on sensitization due to Yb 3+ ions. In particular, the green emission was extremely strong and the Nd 3+ -Yb 3+ -Ho 3+ co doped ZrF 4 based glasses have a high possibility of realizing a green up conversion laser glass. In this paper the up conversion mechanism in the glasses is discussed in detail.展开更多
In this paper we report the observation of multi-photon up-conversion luminescence phenomenon of ErP_(5)O_(14) noncrystalline induced by pulse DCM dye laser and clarify that the mechanism of up-conversion is the step ...In this paper we report the observation of multi-photon up-conversion luminescence phenomenon of ErP_(5)O_(14) noncrystalline induced by pulse DCM dye laser and clarify that the mechanism of up-conversion is the step by step absorption of single Er^(3+)ion.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
Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·(1.95-x)GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 (x=0.02,0.05,0.08,0.11,0.14,0.17)in mole percent.Intense blue(476 ...Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·(1.95-x)GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 (x=0.02,0.05,0.08,0.11,0.14,0.17)in mole percent.Intense blue(476 nm),green(524 and 546 nm)and red(658 nm)emissions which identified from the 1G 4 →3H 6 transition of Tm3+and the(2H 11/2 ,4S 3/2 )→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3+,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er3+ion or the excitation power.In addition,the energy transfer processes among Tm3+,Er3+and Yb3+ions,and up-conversion mechanisms are discussed.展开更多
The Ministry of Science and Technology announced the initial results of 2015 National Science and Technology Prize,recently."Establishment of real-time monitoring system and its applications in wide fields based ...The Ministry of Science and Technology announced the initial results of 2015 National Science and Technology Prize,recently."Establishment of real-time monitoring system and its applications in wide fields based on rare earth nano up-conversion luminescence technology"recommended by the Chinese Medical Association was listed among the second prize.The project was conducted by the Academy of展开更多
We propose a femtosecond laser polarization modulation scheme to control the up-conversion(UC) luminescence in Er^(3+)-doped NaYF_4 nanocrystals dispersed in the silicate glass. We show that the UC luminescence can be...We propose a femtosecond laser polarization modulation scheme to control the up-conversion(UC) luminescence in Er^(3+)-doped NaYF_4 nanocrystals dispersed in the silicate glass. We show that the UC luminescence can be suppressed when the laser polarization is changed from linear through elliptical to circular, and the higher repetition rate will yield the lower control efficiency. We theoretically analyze the physical control mechanism of the UC luminescence polarization modulation by considering on- and near-resonant two-photon absorption, energy transfer up-conversion, and excited state absorption, and show that the polarization control mainly comes from the contribution of near-resonant two-photon absorption. Furthermore, we propose a method to improve the polarization control efficiency of UC luminescence in rare-earth ions by applying a two-color femtosecond laser field.展开更多
Blue,green and red up-conversion luminescence at around 490,545 and 650 nm,which result from the Ho^(3+):~5F_3(?)~5I_8,(~5F_4,~5S_2)(?)~5I_8 and ~5F_5(?)~5I_8 transitions,respectively,were observed in Nd^(3+)-Ho^(3+) ...Blue,green and red up-conversion luminescence at around 490,545 and 650 nm,which result from the Ho^(3+):~5F_3(?)~5I_8,(~5F_4,~5S_2)(?)~5I_8 and ~5F_5(?)~5I_8 transitions,respectively,were observed in Nd^(3+)-Ho^(3+) co-doped oxyfluorotellurite glasses under 800 nm excitation.Among these up-conversion luminescence,the green emission was extremely strong and the blue and red emission intensities were very weak.Selectively strong green up-conversion luminescence of these glasses indicate a high possibility for realizing a green up- conversion laser.Up-conversion processes for the blue,green and red emissions are two-photon processes assisted by Nd^(3+)→Ho^(3+) energy transfer.It is proposed that the up-conversion mechanism for the blue and green emissions is different from that for the red emission.The respective mechanisms are discussed.展开更多
The up-conversion luminescence composite NaYF 4:Er 3+ /TiO 2 is prepared using the sol-gel method.The specimen has good crystallinity and two shapes,i.e.,viereck and round,while the sizes of viereck and round particle...The up-conversion luminescence composite NaYF 4:Er 3+ /TiO 2 is prepared using the sol-gel method.The specimen has good crystallinity and two shapes,i.e.,viereck and round,while the sizes of viereck and round particles are both micron-sized.The TiO 2 has an anatase structure,while the NaYF 4 has a hexagonal phase,which can be hardly obtained through the common sol-gel method.Due to the big particle size and the high crystallinity of pure NaYF 4:Er 3+,the composite has a small specific surface area that is less than Degussa P25 TiO 2.The NaYF 4:Er 3+ /TiO 2 composite shows several emission peaks at 211,237,and 251 nm under the excitation of 388 nm,at 395 nm and 411 nm under the excitation of 500 nm,and at 467,481,492,and 508 nm under the excitation of 570 nm.展开更多
In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly...In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the ~2H_(11/2)/~4S_(3/2)→~4I_(15/2) transitions of Er^(3+),~1G_(4)→~3H_6 transition of Tm^(3+),and_5F_5→~5I_8 transition of Ho^(3+).White luminescence characteristics and mechanisms of up-conversion system were investigated in detail.In addition,the temperature sensing behaviors of multiple levels emission combinations for Na_(3)La(VO_(4))_(2):Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) were analyzed by employing thermally coupled and non-thermally coupled energy levels.Based on the emissions of ~3F_(2,3)/~1G_(4) energy levels,the maximum relative and absolute sensitivities were obtained to be 2.20%/K and 0.279 K^(-1).The design of up-conversion luminescence materials with high-quality white luminescence and excellent sensitivity performance is critical in the field of optical applications.展开更多
A series of YNbO_(4):Bi^(3+) and YNbO_(4):Bi^(3+)/Er^(3+) phosphors were prepared by a conventional high temperature solid-state reaction method.The results of XRD and Rietveld refinement confirm that monoclinic phase...A series of YNbO_(4):Bi^(3+) and YNbO_(4):Bi^(3+)/Er^(3+) phosphors were prepared by a conventional high temperature solid-state reaction method.The results of XRD and Rietveld refinement confirm that monoclinic phase YNbO_(4)samples are achieved.The down-/up-conversion luminescence of Er^(3+) ions was investigated under the excitation of ultraviolet light(327 nm)and near infrared light(980 nm).Under 327 nm excitation,broad visible emission band from Bi^(3+) ions and characteristic green emission peaks from Er^(3+) ions are simultaneously observed,while only strong green emissions from Er^(3+) ions are detected upon excitation of 980 nm.Remarkable emission enhancement is observed in down-/up-conversion luminescence processes by introducing Bi^(3+) ions into Er^(3+)-doped YNbO_(4)phosphors.Pumped current versus up-conversion emission intensity study shows that two-photon processes are responsible for both the green and the red up-conversion emissions of Er^(3+)ion.Through the study of the temperature sensing property of Er^(3+) ion,it is affirmed that the temperature sensitivity is sensitive to the doping concentration of Bi^(3+) ions.By comparing the experimental values of the radiative transition rate ratio of the two green emission levels of Er^(3+) ions and the theoretical values calculated by Judd-Ofelt(J-O)theory,it is concluded that the temperature sensing property of Er^(3+) ions is greatly affected by the energy level splitting.展开更多
Er^(3+)and Yb^(3+)co-doped CaBi_(2)Ta_(2)O_(9)(CBT)-based bismuth layered-structure oxides were synthesized by a simple solid-state reaction method.Their up-conversion(UC)luminescence,dielectric and ferroelectric prop...Er^(3+)and Yb^(3+)co-doped CaBi_(2)Ta_(2)O_(9)(CBT)-based bismuth layered-structure oxides were synthesized by a simple solid-state reaction method.Their up-conversion(UC)luminescence,dielectric and ferroelectric properties were investigated.Two strong green emission bands centered at 526 and 547nm and a weak red emission band centered at 658nm were obtained under a 980nm laser excitation at room temperature.These emission bands originated from the radiative relaxation of Er^(3+)from 2H_(11)=2,4S_(3)=2,and 4F_(9/2) levels to the ground state 4I_(15)=2,respectively.At the meantime,the fluorescence intensity ratio(FIR)variation of two green UC emissions at 526 and 547nm has been studied as a function of temperature in the range of 153–603K.The maximum sensor sensitivity obtained was 39×10^(-4)K^(-1) at 590K,which indicated that Er^(3+)=Yb^(3+)co-doped CBT ceramic is a promising candidate for applications in optical high temperature sensor.展开更多
A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3...A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3+),Er^(3+) were investigated by X-ray diffraction(XRD) and spectral methods.The XRD pattern shows that incorporating different amounts of Yb^(3+)and Er^(3+) have no influence on the phase formation of SrIn_2O_4.The up-conversion luminescence spectrum of SrIn_2O_4:Er^(3+) presented a weak luminescence due to ground state absorption of Er^(3+).However,Yb^(3+)/Er^(3+) codoped SrIn_2O_4 depicted the green(525 and 551 run) and red(662 nm) up-conversion luminescence which were assigned to the energy transfer from the Yb^(3+) transition ~2F_(7/2)-~2F_(5/2) to the Er^(3+) transitions ~2H_(11/2)-~4I_(15/2) and ~4F_(9/2-~4I_(15/2),respectively.The possible up-conversion luminescence mechanism of SrIn_2O_4:Yb^(3+),Er^(3+) was analyzed.All results could be helpful to the development of up-conversion luminescence materials.展开更多
The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controll...The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations.展开更多
The opal photonic crystals(PCs) were assembled by vertical deposition of polystyrene microspheres(PS), in which Yb3+, Er3+ co-doped ZnO powders were deposited on the surface of PC films. The phase, structure and morph...The opal photonic crystals(PCs) were assembled by vertical deposition of polystyrene microspheres(PS), in which Yb3+, Er3+ co-doped ZnO powders were deposited on the surface of PC films. The phase, structure and morphology of the obtained samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscope(TEM). The performance of up-conversion photoluminescence(UCPL) was investigated by fluorescence spectrophotometer. The up-conversion(UC) emission of Zn O:Yb3+/Er3+ on the PC surface is notably enhanced when the UC emission wavelength is overlapped with the photonic bandgaps of opals, which is attributed to Bragg reflection of photonic bandgap. The results show that PCs may have potential applications in the enhancement of UCPL and optoelectronic devices.展开更多
基金supported by the Korea Science and Engineering Foundation (KOSEF) Grant funded by the Korean Government (MEST) (2009-0078682)
文摘The luminescence of Nd3+-doped in NaBi(WO4)2 single crystal was investigated from 10 K to room temperature.The excitation source was a pulsed dye laser in resonance into the(4G5/2+2G(1)7/2) levels of Nd3+ ions.Several blue emission bands in the up-conversion luminescence spectra corresponded to transitions from 2P1/2 to 4I9/2.Some violet bands corresponding to transitions of 4D3/2→(4I9/2,4I11/2,4I13/2) were also observed.For comparison,the luminescence spectra and decay curves excited by the pulsed 355 nm laser were measured.In order to investigate up-conversion mechanisms,the decay behavior and the dependence of the up-conversion luminescence on laser powers were investigated.The temporal decay behavior of the up-conversion luminescence indicated that the two-photon excited state absorption of the Nd3+ ions was the dominant mechanism in this crystal.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51132004,11474096,11604199,U1704145,and 11747101)the Fund from the Science and Technology Commission of Shanghai Municipality,China(Grant No.14JC1401500)+1 种基金the Henan Provincial Natural Science Foundation,China(Grant No.182102210117)the Higher Educational Key Program of Henan Province of China(Gant Nos.17A140025 and 16A140030)
文摘The up-conversion luminescence tuning of rare-earth ions is an important research topic for understanding luminescence mechanisms and promoting related applications. In this paper, we experimentally study the up-conversion luminescence tuning of Er^(3+)-doped ceramic glass excited by the unshaped, V-shaped and cosine-shaped femtosecond laser field with different laser powers. The results show that green and red up-conversion luminescence can be effectively tuned by varying the power or spectral phase of the femtosecond laser field. We further analyze the up-conversion luminescence tuning mechanism by considering different excitation processes, including single-photon absorption(SPA), two-photon absorption(TPA), excited state absorption(ESA), and energy transfer up-conversion(ETU). The relative weight of TPA in the whole excitation process can increase with the increase of the laser power, thereby enhancing the intensity ratio between green and red luminescence(I_(547)/I_(656)). However, the second ETU(ETU2) process can generate red luminescence and reduce the green and red luminescence intensity ratio I_(547)/I_(656), while the third ESA(ESA3) process can produce green luminescence and enhance its control efficiency. Moreover, the up-conversion luminescence tuning mechanism is further validated by observing the up-conversion luminescence intensity, depending on the laser power and the down-conversion luminescence spectrum under the excitation of 400-nm femtosecond laser pulse. These studies can present a clear physical picture that enables us to understand the up-conversion luminescence tuning mechanism in rare-earth ions, and can also provide an opportunity to tune up-conversion luminescence to promote its related applications.
基金the National Natural Science Foundation of China (Nos. 50372006, 20273007, and 20407003).
文摘The surface of an up-conversion luminescence material was modified by overcoating with SiO2, which was syn- thesized from a hydrolysis progress of tetraethoxysilane (TEOS) in alkalescent condition. By analyzing the hydrolyzed mechanism of TEOS, it was found that there was not only physical adsorption but also chemical bonding between the up-conversion material and SiO2. At the same time, some adsorption bands at 1100, 475, 950, and 3500 cm?1 were found by FI-IR, which were the characteristic bands of Si?OH and Si?O?Si. By analyzing the surface elements of the coated material by XPS, it was found that its surface only included Si, O, and C elements, and not F and Y. In the picture of XRD, there was no additional peak after surface modification, suggesting that the silica shell was amorphous. The small peak at 2θ = 23° in the X-ray diffraction pattern of the coated material was caused by the amorphous SiO2 shell, and the TEM image also proved that the surface of the material was successfully modified by overcoating with SiO2. The amount of hydroxyls was then increased on the surface of the material, which made it easy to connect with other active groups.
基金the National Natural Science Foundations of China (No50372006 and No20273007)
文摘A new method was reported for surface modification of an up-conversion luminescence material with hydrosulfide group. The factors that may influence the surface modification,such as reaction time,amount of catalyzer and modifier,and reaction solvent,were investigated. The optimal conditions were that the reaction time,the quantity of the basic catalyzer,the quantity of modifier and the volume of reaction solvent were 40 min,1.0,1.0,and 40 mL,respectively. The results indicated that hydrosulfide group content modified on the surface of up-conversion luminescence material reached to 0.1430 mmol/g,and this modified up-conversion lumi-nescence material could be widely used in the study of structure of protein and the property of microenvironment.
文摘Up conversion processes for the blue, green and red emissions were found two photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd 3+ →Yb 3+ → Ho 3+ energy transfer. The strong green emission due to the Ho 3+ : ( 5F 4 , 5S 2) → 5I 8 transitions was observed in Nd 3+ - Ho 3+ co doped ZrF 4 based fluoride glasses under 800 nm excitation. As an attempt to enhance Ho 3+ up conversion luminescences in the Nd 3+ - Ho 3+ co doped ZrF 4 based glasses, Yb 3+ ions were added to the glasses. As a result it was found that, in 800 nm excitation of 60ZrF 4. 30BaF2. (8- x )LaF 3. 1NdF 3. x YbF 3. 1HoF 3 glasses ( x =0 to 7), sensitized up conversion luminescences are observed at around 490 nm (blue), 545 nm (green), and 650 nm (red), which correspond to the Ho 3+ : 5F 3 → 5I 8 , ( 5F 4 , 5S 2) → 5I 8 and 5F 5 → 5I 8 transitions respectively. The intensities of the green and red emissions in a 3 mol % YbF 3 containing glass were about 50 times stronger than those glasses without YbF 3. This is based on sensitization due to Yb 3+ ions. In particular, the green emission was extremely strong and the Nd 3+ -Yb 3+ -Ho 3+ co doped ZrF 4 based glasses have a high possibility of realizing a green up conversion laser glass. In this paper the up conversion mechanism in the glasses is discussed in detail.
文摘In this paper we report the observation of multi-photon up-conversion luminescence phenomenon of ErP_(5)O_(14) noncrystalline induced by pulse DCM dye laser and clarify that the mechanism of up-conversion is the step by step absorption of single Er^(3+)ion.
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Funded by the National Natural Science Foundation of China (No. 50772045)the Society Development Foundation of Yunnan Province (No. 2007E036M)
文摘Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·(1.95-x)GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 (x=0.02,0.05,0.08,0.11,0.14,0.17)in mole percent.Intense blue(476 nm),green(524 and 546 nm)and red(658 nm)emissions which identified from the 1G 4 →3H 6 transition of Tm3+and the(2H 11/2 ,4S 3/2 )→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3+,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er3+ion or the excitation power.In addition,the energy transfer processes among Tm3+,Er3+and Yb3+ions,and up-conversion mechanisms are discussed.
文摘The Ministry of Science and Technology announced the initial results of 2015 National Science and Technology Prize,recently."Establishment of real-time monitoring system and its applications in wide fields based on rare earth nano up-conversion luminescence technology"recommended by the Chinese Medical Association was listed among the second prize.The project was conducted by the Academy of
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11304396)the National Natural Science Foundation of China(Grant Nos.11474096 and 51132004)the Shanghai Municipal Science and Technology Commission,China(Grant No.14JC1401500)
文摘We propose a femtosecond laser polarization modulation scheme to control the up-conversion(UC) luminescence in Er^(3+)-doped NaYF_4 nanocrystals dispersed in the silicate glass. We show that the UC luminescence can be suppressed when the laser polarization is changed from linear through elliptical to circular, and the higher repetition rate will yield the lower control efficiency. We theoretically analyze the physical control mechanism of the UC luminescence polarization modulation by considering on- and near-resonant two-photon absorption, energy transfer up-conversion, and excited state absorption, and show that the polarization control mainly comes from the contribution of near-resonant two-photon absorption. Furthermore, we propose a method to improve the polarization control efficiency of UC luminescence in rare-earth ions by applying a two-color femtosecond laser field.
基金Supported by the National Natural Science Foundation of China (No.50772045)
文摘Blue,green and red up-conversion luminescence at around 490,545 and 650 nm,which result from the Ho^(3+):~5F_3(?)~5I_8,(~5F_4,~5S_2)(?)~5I_8 and ~5F_5(?)~5I_8 transitions,respectively,were observed in Nd^(3+)-Ho^(3+) co-doped oxyfluorotellurite glasses under 800 nm excitation.Among these up-conversion luminescence,the green emission was extremely strong and the blue and red emission intensities were very weak.Selectively strong green up-conversion luminescence of these glasses indicate a high possibility for realizing a green up- conversion laser.Up-conversion processes for the blue,green and red emissions are two-photon processes assisted by Nd^(3+)→Ho^(3+) energy transfer.It is proposed that the up-conversion mechanism for the blue and green emissions is different from that for the red emission.The respective mechanisms are discussed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 20876125)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20096101110013)the Northwest University Graduate Cross-Discipline Funds (Grant Nos. 09YJC27,09YJC24,and 201031)
文摘The up-conversion luminescence composite NaYF 4:Er 3+ /TiO 2 is prepared using the sol-gel method.The specimen has good crystallinity and two shapes,i.e.,viereck and round,while the sizes of viereck and round particles are both micron-sized.The TiO 2 has an anatase structure,while the NaYF 4 has a hexagonal phase,which can be hardly obtained through the common sol-gel method.Due to the big particle size and the high crystallinity of pure NaYF 4:Er 3+,the composite has a small specific surface area that is less than Degussa P25 TiO 2.The NaYF 4:Er 3+ /TiO 2 composite shows several emission peaks at 211,237,and 251 nm under the excitation of 388 nm,at 395 nm and 411 nm under the excitation of 500 nm,and at 467,481,492,and 508 nm under the excitation of 570 nm.
基金Project supported by the National Natural Science Foundation of China (11904046,11974069,11504039)。
文摘In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the ~2H_(11/2)/~4S_(3/2)→~4I_(15/2) transitions of Er^(3+),~1G_(4)→~3H_6 transition of Tm^(3+),and_5F_5→~5I_8 transition of Ho^(3+).White luminescence characteristics and mechanisms of up-conversion system were investigated in detail.In addition,the temperature sensing behaviors of multiple levels emission combinations for Na_(3)La(VO_(4))_(2):Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) were analyzed by employing thermally coupled and non-thermally coupled energy levels.Based on the emissions of ~3F_(2,3)/~1G_(4) energy levels,the maximum relative and absolute sensitivities were obtained to be 2.20%/K and 0.279 K^(-1).The design of up-conversion luminescence materials with high-quality white luminescence and excellent sensitivity performance is critical in the field of optical applications.
基金Project supported by the National Natural Science Foundation of China(11774042,11704056)Fundamental Research Funds for the Central Universities(3132020177,3132019338)。
文摘A series of YNbO_(4):Bi^(3+) and YNbO_(4):Bi^(3+)/Er^(3+) phosphors were prepared by a conventional high temperature solid-state reaction method.The results of XRD and Rietveld refinement confirm that monoclinic phase YNbO_(4)samples are achieved.The down-/up-conversion luminescence of Er^(3+) ions was investigated under the excitation of ultraviolet light(327 nm)and near infrared light(980 nm).Under 327 nm excitation,broad visible emission band from Bi^(3+) ions and characteristic green emission peaks from Er^(3+) ions are simultaneously observed,while only strong green emissions from Er^(3+) ions are detected upon excitation of 980 nm.Remarkable emission enhancement is observed in down-/up-conversion luminescence processes by introducing Bi^(3+) ions into Er^(3+)-doped YNbO_(4)phosphors.Pumped current versus up-conversion emission intensity study shows that two-photon processes are responsible for both the green and the red up-conversion emissions of Er^(3+)ion.Through the study of the temperature sensing property of Er^(3+) ion,it is affirmed that the temperature sensitivity is sensitive to the doping concentration of Bi^(3+) ions.By comparing the experimental values of the radiative transition rate ratio of the two green emission levels of Er^(3+) ions and the theoretical values calculated by Judd-Ofelt(J-O)theory,it is concluded that the temperature sensing property of Er^(3+) ions is greatly affected by the energy level splitting.
基金This work was supported by the Natural Science Foundation of China(No.51072136).
文摘Er^(3+)and Yb^(3+)co-doped CaBi_(2)Ta_(2)O_(9)(CBT)-based bismuth layered-structure oxides were synthesized by a simple solid-state reaction method.Their up-conversion(UC)luminescence,dielectric and ferroelectric properties were investigated.Two strong green emission bands centered at 526 and 547nm and a weak red emission band centered at 658nm were obtained under a 980nm laser excitation at room temperature.These emission bands originated from the radiative relaxation of Er^(3+)from 2H_(11)=2,4S_(3)=2,and 4F_(9/2) levels to the ground state 4I_(15)=2,respectively.At the meantime,the fluorescence intensity ratio(FIR)variation of two green UC emissions at 526 and 547nm has been studied as a function of temperature in the range of 153–603K.The maximum sensor sensitivity obtained was 39×10^(-4)K^(-1) at 590K,which indicated that Er^(3+)=Yb^(3+)co-doped CBT ceramic is a promising candidate for applications in optical high temperature sensor.
文摘A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3+),Er^(3+) were investigated by X-ray diffraction(XRD) and spectral methods.The XRD pattern shows that incorporating different amounts of Yb^(3+)and Er^(3+) have no influence on the phase formation of SrIn_2O_4.The up-conversion luminescence spectrum of SrIn_2O_4:Er^(3+) presented a weak luminescence due to ground state absorption of Er^(3+).However,Yb^(3+)/Er^(3+) codoped SrIn_2O_4 depicted the green(525 and 551 run) and red(662 nm) up-conversion luminescence which were assigned to the energy transfer from the Yb^(3+) transition ~2F_(7/2)-~2F_(5/2) to the Er^(3+) transitions ~2H_(11/2)-~4I_(15/2) and ~4F_(9/2-~4I_(15/2),respectively.The possible up-conversion luminescence mechanism of SrIn_2O_4:Yb^(3+),Er^(3+) was analyzed.All results could be helpful to the development of up-conversion luminescence materials.
基金the Na-tional Natural Science Foundation of China(Grant Nos.91850202,11774094,11727810,11804097,and 61720106009)the Science and Technology Commission of Shanghai Municipality(Grant No.17ZR146900)+1 种基金the China Postdoctoral Science Foundation(Grant No.2018M641958)ECNU Academic Innovation Promotion Program for Excellent Doctoral Students(Grant No.YBNLTS2019-011).
文摘The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations.
基金supported by the National Natural Science Foundation of China(No.61274064)
文摘The opal photonic crystals(PCs) were assembled by vertical deposition of polystyrene microspheres(PS), in which Yb3+, Er3+ co-doped ZnO powders were deposited on the surface of PC films. The phase, structure and morphology of the obtained samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscope(TEM). The performance of up-conversion photoluminescence(UCPL) was investigated by fluorescence spectrophotometer. The up-conversion(UC) emission of Zn O:Yb3+/Er3+ on the PC surface is notably enhanced when the UC emission wavelength is overlapped with the photonic bandgaps of opals, which is attributed to Bragg reflection of photonic bandgap. The results show that PCs may have potential applications in the enhancement of UCPL and optoelectronic devices.
