In the present paper, the concentration effect of near-infrared quantum cutting of Tm3+ ion in (Y1-xTmx)3Al5Ol2 powder phosphor is studied by means of experiments and calculations. In addition, the absorption spect...In the present paper, the concentration effect of near-infrared quantum cutting of Tm3+ ion in (Y1-xTmx)3Al5Ol2 powder phosphor is studied by means of experiments and calculations. In addition, the absorption spectra, visible-to-near- infrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that (Y1-xTmx)3Al5O12 powder phosphor has a strong four-photon near-infrared quantum cutting luminescence of 1788.0-nm 3F4 →3H6 fluores- cence of Tm3+ ion, when excited by 357.0-nm light. It is also found that the up-limit of the four-photon near-infrared quantum cutting luminescence efficiency of (Yo.700Tmo.300)3Al5 O12 powder phosphor is approximately 302.19%. To the knowledge of the authors, this is the first time that a near-infrared quantum cutting efficiency up-limit exceeding 300% has been reported. The results of this manuscript are valuable in aiding the probing of the new generation Ge solar cell.展开更多
The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting m...The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting mechanism of pr3+-yb3+ in the near infrared region was proposed and the fluorescence lifetime and quantum efficiency was calculated. The results indicate that the main phase in the oxyfluoride glass- ceramics is CaF2 nanocrystal sized at 30 nm. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) have proved the incorporation of Pr3+ and Yb3+ into CaF2 nanocrystal lattice, Near-infrared quantum cutting involving Yb3+ 980 nm and 1 015 tun (2F5/2→2F7/2) emission has been achieved upon the excitation of the 3P0 energy level of Pr3+ at 482 nm. The fluorescence lifetime decreases sharply and quantum efficiency increases with increasing Yb3+ concentration, and the optimal quantum efficiency reaches 191%.展开更多
Tb^(3+) and Yb^(3+) codoped LuPO_4 phosphors were prepared by the reverse-strike co-precipitation method.The obtained LuPO_4:Tb^(3+),Yb^(3+) phosphors were characterized by X-ray diffraction(XRD),photol...Tb^(3+) and Yb^(3+) codoped LuPO_4 phosphors were prepared by the reverse-strike co-precipitation method.The obtained LuPO_4:Tb^(3+),Yb^(3+) phosphors were characterized by X-ray diffraction(XRD),photoluminescence(PL) spectra and decay kinetics to understand the near-infrared quantum cutting(QC) phenomena.The XRD results showed that all the phosphors exhibited good crystallinity and had a pure tetragonal phase of LuPO_4.The experimental results showed that the strong green emission around 545 nm from Tb^(3+)(~5D_4→~7F_5) and near-infrared(NIR) emission at 1003 nm from Yb^(3+)(~2F_(5/2)→~2F_(7/2)) of LuPO_4:Tb^(3+),Yb^(3+)phosphors were observed under 489 nm excitation,respectively.The Yb^(3+) concentration dependence on luminescent properties and lifetimes of both the visible and NIR emissions were also investigated.The quenching concentration of Yb^(3+) ions approached as high as 10 mol.%.The excellent luminescence properties of the LuPO_4:Tb^(3+),Yb^(3+) indicated its potential application in improving the energy conversion efficiency of the silicon based solar cells by converting one blue photon to two NIR ones.展开更多
Ce3+ and Yb3+ co-activated GdBO3 phosphors were prepared by a conventional solid-state reaction method. X-ray powder diffraction, photoluminescent spectra and decay curves were used to characterize their structural ...Ce3+ and Yb3+ co-activated GdBO3 phosphors were prepared by a conventional solid-state reaction method. X-ray powder diffraction, photoluminescent spectra and decay curves were used to characterize their structural and luminescent properties. An efficient near-infrared (NIR) quantum cutting (QC) from the phosphors was observed, which involved the emission of two low-energy NIR photons (around 971 nm) from an absorbed ultra-violet (UV) photon at 358 nm via a cooperative energy transfer (CET) from Ce3+ to Yb3+ ions. The theoretical quantum efficiency was calculated and the maximum efficiency approached up to 164% before reaching the critical concentration quenching threshold. Our results demonstrated that these phosphors might find potential application in improving the efficiency of silicon based solar cells.展开更多
This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It ...This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It summarizes the strategies of how to synthesize high efficiency PbX QDs and how to realize high performance Pb X based NIR-QLEDs.展开更多
The infrared quantum cutting of oxyfluoride nanophase vitroceramics Tb(0.7)Yb(3):FOV has been studied in the present paper. The actual quantum cutting efficiency formula calculated from integral fluorescence inte...The infrared quantum cutting of oxyfluoride nanophase vitroceramics Tb(0.7)Yb(3):FOV has been studied in the present paper. The actual quantum cutting efficiency formula calculated from integral fluorescence intensity is extended to the case of Tb(0.7)Yb(3):FOV. The visible and the infrared fluorescence spectra and their integral fluorescence intensities are measured from static fluorescence experiment. Lifetime curve is measured from dynamic fluorescence experiment. It is found that the total actual quantum cutting efficiency n of the excited 5D4 level is about 93.7%, and that of excited (5D3, 5G6) levels is 93.5%. It is also found that the total theoretical quantum cutting efficiency upper limit ?~x^Yb of the 485.5 nm excited 5D4 level is about 121.7%, and that of 378.5 nm excited (5D3, 5G6) levels is 137.2%.展开更多
High-efficiency and low-cost near-infrared(NIR)emitting quantum dots(QDs)are highly desirable for next-generation intrinsically flexible NIR light sources.Halide passivation is commonly employed to passivate surface t...High-efficiency and low-cost near-infrared(NIR)emitting quantum dots(QDs)are highly desirable for next-generation intrinsically flexible NIR light sources.Halide passivation is commonly employed to passivate surface traps to obtain high-quality NIRemitting PbS QDs,but this procedure requires high temperature and inert atmospheres.Here we develop a facile roomtemperature halide passivation method for highly efficient NIR-emitting PbS QDs by employing crown ethers as a unique auxiliary additive.Experimental and theoretical investigations reveal that the formation of K^(+)-crown ethers complex effectively facilitates the dissociation of KCl in toluene and releases more Cl^(−)ions for extraordinary halide passivation at room temperature and in the air,thus improving the photoluminescence quantum yield from 24%to 35%in solution and further to 44%in blend films.The well-passivated PbS QD films are integrated with red organic light-emitting diodes(OLEDs)and the resulting QDOLEDs exhibit high-performance NIR emission centered at 887 nm,a high external quantum efficiency of 5.2%at a radiance of 10 W·sr^(−1)·m^(−2),superior operational stability with long lifetime T90 of 188 h at the current density of 25 mA·cm^(−2).We also construct a large-area NIR QD-OLED(5 cm×5 cm)with desirable uniform emission.This work opens a new avenue to achieve robust large-area NIR planar light sources for broad applications.展开更多
We developed the high-gravity coupled liquid-liquid interface reaction technique on the basis of the rotating packed bed(RPB)reactor for the continuous and ultrafast synthesis of silver sulfide(Ag2S)quantum dots(QDs)w...We developed the high-gravity coupled liquid-liquid interface reaction technique on the basis of the rotating packed bed(RPB)reactor for the continuous and ultrafast synthesis of silver sulfide(Ag2S)quantum dots(QDs)with near-infrared(NIR)luminescence.The formation of Ag2S QDs occurs at the interface of microdroplets,and the average size of Ag2S QDs was 4.5 nm with a narrow size distribution.Ag2S QDs can disperse well in various organic solvents and exhibit NIR luminescence with a peak wavelength at 1270 nm under 980-nm laser excitation.The mechanism of the process intensification was revealed by both the computational fluid dynamics simulation and fluorescence imaging,and the mechanism is attributed to the small and uniform droplet formation in the RPB reactor.This study provides a novel approach for the continuous and ultrafast synthesis of NIR Ag2S QDs for potential scale-up.展开更多
We study the behavior of quantum Fisher information for a qubit probe that is interacting with a squeezed thermal environment. We analyzed the effect of squeezing parameters on the dynamics of quantum Fisher informati...We study the behavior of quantum Fisher information for a qubit probe that is interacting with a squeezed thermal environment. We analyzed the effect of squeezing parameters on the dynamics of quantum Fisher information which affects the optimal precision of the estimation parameter. We show that the squeezed field may offer a significant role in the precise measurement of the parameter cut-off frequency which is linked to the environment correlation time. Our results may be useful in quantum metrology, communication, and quantum estimation processes.展开更多
High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach.This engineered quantum dots with unique near-infrared(NIR)fluorescence,possessing outstanding optical properties,and the ...High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach.This engineered quantum dots with unique near-infrared(NIR)fluorescence,possessing outstanding optical properties,and the biocompatibility desired for in vivo applications.The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive dots containing elements such as cadmium,mercury,or lead.Also,these newly developed ultrasmall non-Cd containing and NIR-emitting quantum dots showed signifi cantly improved circulation half-life and minimal reticuloendothelial system(RES)uptake.展开更多
Conventional photoluminescence(PL)yields at most one emitted photon for each absorption event.Downconversion(or quantum cutting)materials can yield more than one photon by virtue of energy transfer processes between l...Conventional photoluminescence(PL)yields at most one emitted photon for each absorption event.Downconversion(or quantum cutting)materials can yield more than one photon by virtue of energy transfer processes between luminescent centers.In this work,we introduce Gd2O2S:Tm^(3+) as a multi-photon quantum cutter.It can convert near-infrared,visible,or ultraviolet photons into two,three,or four infrared photons of,1800 nm,respectively.The cross-relaxation steps between Tm^(3+) ions that lead to quantum cutting are identified from(time-resolved)PL as a function of the Tm^(3+) concentration in the crystal.A model is presented that reproduces the way in which the Tm^(3+) concentration affects both the relative intensities of the various emission lines and the excited state dynamics and providing insight in the quantum cutting efficiency.Finally,we discuss the potential application of Gd2O2S:Tm^(3+) for spectral conversion to improve the efficiency of next-generation photovoltaics.展开更多
With the rapid growth of optical communications traffic,the demand for broadband optical amplifiers continues to increase.It is necessary to develop a gain medium that covers more optical communication bands.We precip...With the rapid growth of optical communications traffic,the demand for broadband optical amplifiers continues to increase.It is necessary to develop a gain medium that covers more optical communication bands.We precipitated PbS quantum dots(QDs) and Ba F_(2):Tm^(3+) nanocrystals (NCs) in the same glass to form two independent emission centers.The Ba F_(2)NCs in the glass can provide a crystal field environment with low phonon energy for rare earth (RE) ions and prevent the energy transfer between RE ions and PbS QDs.By adjusting the heat treatment schedule,the emission of the two luminescence centers from PbS QDs and Tm^(3+) ions perfectly splices and covers the ultra-broadband near-infrared emission from 1200 nm to 2000 nm with bandwidth over 430 nm.Therefore,it is expected to be a promising broadband gain medium for fiber amplifiers.展开更多
The emission and excitation spectra of Gd2SiO5: Eu3+ were investigated using the VUVbeam line of the Beijing Synchrotron Radiation Facility (BSRF). The experimental results werediscussed in the frame of visible quantu...The emission and excitation spectra of Gd2SiO5: Eu3+ were investigated using the VUVbeam line of the Beijing Synchrotron Radiation Facility (BSRF). The experimental results werediscussed in the frame of visible quantum cutting process involved in Gd3+-Eu3+ system. Upon di-rect excitation into the 6GJ states of Gd3+, two visible photon emissions from Eu3+ were observed.Cursory evaluation proved that Gd2SiO5: Eu3+ is an efficient visible quantum cutter.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.10674019)the Significant Project of Fundamental Research Funds for the Central Universities of China(Grant No.212-105560GK)
文摘In the present paper, the concentration effect of near-infrared quantum cutting of Tm3+ ion in (Y1-xTmx)3Al5Ol2 powder phosphor is studied by means of experiments and calculations. In addition, the absorption spectra, visible-to-near- infrared excitation and emission spectra, and fluorescence lifetimes are measured. It is found that (Y1-xTmx)3Al5O12 powder phosphor has a strong four-photon near-infrared quantum cutting luminescence of 1788.0-nm 3F4 →3H6 fluores- cence of Tm3+ ion, when excited by 357.0-nm light. It is also found that the up-limit of the four-photon near-infrared quantum cutting luminescence efficiency of (Yo.700Tmo.300)3Al5 O12 powder phosphor is approximately 302.19%. To the knowledge of the authors, this is the first time that a near-infrared quantum cutting efficiency up-limit exceeding 300% has been reported. The results of this manuscript are valuable in aiding the probing of the new generation Ge solar cell.
基金Funded by Key Laboratory for Ultrafine Materials of Ministry of Education(No.08DZ2230500),School of Materials Science and Engineering,East China University of Science and Technology
文摘The Pr3+-Yb3+ co-doped oxyfluoride glass-ceramics containing CaF2 nanocrystals were obtained by thermal treatment on the as-made glasses. The structure of fluoride nanocrystals was investigated. The light-emitting mechanism of pr3+-yb3+ in the near infrared region was proposed and the fluorescence lifetime and quantum efficiency was calculated. The results indicate that the main phase in the oxyfluoride glass- ceramics is CaF2 nanocrystal sized at 30 nm. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) have proved the incorporation of Pr3+ and Yb3+ into CaF2 nanocrystal lattice, Near-infrared quantum cutting involving Yb3+ 980 nm and 1 015 tun (2F5/2→2F7/2) emission has been achieved upon the excitation of the 3P0 energy level of Pr3+ at 482 nm. The fluorescence lifetime decreases sharply and quantum efficiency increases with increasing Yb3+ concentration, and the optimal quantum efficiency reaches 191%.
基金supported by the National Natural Science Foundation of China(11404047,11674044,11604037)Chongqing Research Program of Basic Research and Frontier Technology(CSTC2016JCYJA0113,CSTC2016JCYJA0207,CSTC2015JCYJA50005)Research Training Program for Undergraduates of Chongqing University of Posts and Telecommunications(A2015-86,A2016-53)
文摘Tb^(3+) and Yb^(3+) codoped LuPO_4 phosphors were prepared by the reverse-strike co-precipitation method.The obtained LuPO_4:Tb^(3+),Yb^(3+) phosphors were characterized by X-ray diffraction(XRD),photoluminescence(PL) spectra and decay kinetics to understand the near-infrared quantum cutting(QC) phenomena.The XRD results showed that all the phosphors exhibited good crystallinity and had a pure tetragonal phase of LuPO_4.The experimental results showed that the strong green emission around 545 nm from Tb^(3+)(~5D_4→~7F_5) and near-infrared(NIR) emission at 1003 nm from Yb^(3+)(~2F_(5/2)→~2F_(7/2)) of LuPO_4:Tb^(3+),Yb^(3+)phosphors were observed under 489 nm excitation,respectively.The Yb^(3+) concentration dependence on luminescent properties and lifetimes of both the visible and NIR emissions were also investigated.The quenching concentration of Yb^(3+) ions approached as high as 10 mol.%.The excellent luminescence properties of the LuPO_4:Tb^(3+),Yb^(3+) indicated its potential application in improving the energy conversion efficiency of the silicon based solar cells by converting one blue photon to two NIR ones.
基金Project supported by the National Natural Science Foundation of China (10904131)Student Scientific Activities Programme (Emerging Artists Talents Scheme) of Zhejiang Province (2010R404067)
文摘Ce3+ and Yb3+ co-activated GdBO3 phosphors were prepared by a conventional solid-state reaction method. X-ray powder diffraction, photoluminescent spectra and decay curves were used to characterize their structural and luminescent properties. An efficient near-infrared (NIR) quantum cutting (QC) from the phosphors was observed, which involved the emission of two low-energy NIR photons (around 971 nm) from an absorbed ultra-violet (UV) photon at 358 nm via a cooperative energy transfer (CET) from Ce3+ to Yb3+ ions. The theoretical quantum efficiency was calculated and the maximum efficiency approached up to 164% before reaching the critical concentration quenching threshold. Our results demonstrated that these phosphors might find potential application in improving the efficiency of silicon based solar cells.
基金Project supported by the National Key Research and Development Program,China(Grant Nos.2016YFB0401702 and 2017YFE0120400)the National Natural Science Foundation of China(Grant Nos.61875082 and 61405089)+6 种基金the Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting,China(Grant No.2017KSYS007)the Natural Science Foundation of Guangdong,China(Grant No.2017B030306010)the Guangdong Province’s 2018–2019 Key R&D Program:Environmentally Friendly Quantum Dots Luminescent Materials,China(Grant No.2019B010924001)the Shenzhen Innovation Project,China(Grant Nos.JCYJ20160301113356947 and JSGG20170823160757004)the Shenzhen Peacock Team Project,China(Grant No.KQTD2016030111203005)the Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting,China(Grant No.ZDSYS201707281632549)the Tianjin New Materials Science and Technology Key Project,China(Grant No.16ZXCLGX00040)
文摘This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It summarizes the strategies of how to synthesize high efficiency PbX QDs and how to realize high performance Pb X based NIR-QLEDs.
基金supported by the National Natural Science Foundation of China (Grant No. 10674019)
文摘The infrared quantum cutting of oxyfluoride nanophase vitroceramics Tb(0.7)Yb(3):FOV has been studied in the present paper. The actual quantum cutting efficiency formula calculated from integral fluorescence intensity is extended to the case of Tb(0.7)Yb(3):FOV. The visible and the infrared fluorescence spectra and their integral fluorescence intensities are measured from static fluorescence experiment. Lifetime curve is measured from dynamic fluorescence experiment. It is found that the total actual quantum cutting efficiency n of the excited 5D4 level is about 93.7%, and that of excited (5D3, 5G6) levels is 93.5%. It is also found that the total theoretical quantum cutting efficiency upper limit ?~x^Yb of the 485.5 nm excited 5D4 level is about 121.7%, and that of 378.5 nm excited (5D3, 5G6) levels is 137.2%.
基金the National Key Research and Development Program of China(No.2020YFA0715000)the National Natural Science Foundation of China(No.51773109).
文摘High-efficiency and low-cost near-infrared(NIR)emitting quantum dots(QDs)are highly desirable for next-generation intrinsically flexible NIR light sources.Halide passivation is commonly employed to passivate surface traps to obtain high-quality NIRemitting PbS QDs,but this procedure requires high temperature and inert atmospheres.Here we develop a facile roomtemperature halide passivation method for highly efficient NIR-emitting PbS QDs by employing crown ethers as a unique auxiliary additive.Experimental and theoretical investigations reveal that the formation of K^(+)-crown ethers complex effectively facilitates the dissociation of KCl in toluene and releases more Cl^(−)ions for extraordinary halide passivation at room temperature and in the air,thus improving the photoluminescence quantum yield from 24%to 35%in solution and further to 44%in blend films.The well-passivated PbS QD films are integrated with red organic light-emitting diodes(OLEDs)and the resulting QDOLEDs exhibit high-performance NIR emission centered at 887 nm,a high external quantum efficiency of 5.2%at a radiance of 10 W·sr^(−1)·m^(−2),superior operational stability with long lifetime T90 of 188 h at the current density of 25 mA·cm^(−2).We also construct a large-area NIR QD-OLED(5 cm×5 cm)with desirable uniform emission.This work opens a new avenue to achieve robust large-area NIR planar light sources for broad applications.
基金supported by the National Natural Science Foundation of China(No.21808009)the Beijing Natural Science Foundation(No.2182051).
文摘We developed the high-gravity coupled liquid-liquid interface reaction technique on the basis of the rotating packed bed(RPB)reactor for the continuous and ultrafast synthesis of silver sulfide(Ag2S)quantum dots(QDs)with near-infrared(NIR)luminescence.The formation of Ag2S QDs occurs at the interface of microdroplets,and the average size of Ag2S QDs was 4.5 nm with a narrow size distribution.Ag2S QDs can disperse well in various organic solvents and exhibit NIR luminescence with a peak wavelength at 1270 nm under 980-nm laser excitation.The mechanism of the process intensification was revealed by both the computational fluid dynamics simulation and fluorescence imaging,and the mechanism is attributed to the small and uniform droplet formation in the RPB reactor.This study provides a novel approach for the continuous and ultrafast synthesis of NIR Ag2S QDs for potential scale-up.
文摘We study the behavior of quantum Fisher information for a qubit probe that is interacting with a squeezed thermal environment. We analyzed the effect of squeezing parameters on the dynamics of quantum Fisher information which affects the optimal precision of the estimation parameter. We show that the squeezed field may offer a significant role in the precise measurement of the parameter cut-off frequency which is linked to the environment correlation time. Our results may be useful in quantum metrology, communication, and quantum estimation processes.
基金This work was supported in part by the National Cancer Institute(NCI)(R21 CA121842,P50 CA114747,and U54 CA119367)the National Institute of Health(R43 EB005072)the National Science Foundation(CHE-0554812).
文摘High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach.This engineered quantum dots with unique near-infrared(NIR)fluorescence,possessing outstanding optical properties,and the biocompatibility desired for in vivo applications.The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive dots containing elements such as cadmium,mercury,or lead.Also,these newly developed ultrasmall non-Cd containing and NIR-emitting quantum dots showed signifi cantly improved circulation half-life and minimal reticuloendothelial system(RES)uptake.
基金Financial support from the National Science Foundation of China(51125005 and 51472088)is gratefully acknowledgedDechao Yu thanks the China Scholarship Council(CSC,File No.201206150022)for a scholarshipThis work is part of the research program of the‘Stichting voor Fundamenteel Onderzoek der Materie(FOM)’,which is financially supported by the‘Nederlandse Organisatie voor Wetenschappelijk Onderzoek(NWO)’.
文摘Conventional photoluminescence(PL)yields at most one emitted photon for each absorption event.Downconversion(or quantum cutting)materials can yield more than one photon by virtue of energy transfer processes between luminescent centers.In this work,we introduce Gd2O2S:Tm^(3+) as a multi-photon quantum cutter.It can convert near-infrared,visible,or ultraviolet photons into two,three,or four infrared photons of,1800 nm,respectively.The cross-relaxation steps between Tm^(3+) ions that lead to quantum cutting are identified from(time-resolved)PL as a function of the Tm^(3+) concentration in the crystal.A model is presented that reproduces the way in which the Tm^(3+) concentration affects both the relative intensities of the various emission lines and the excited state dynamics and providing insight in the quantum cutting efficiency.Finally,we discuss the potential application of Gd2O2S:Tm^(3+) for spectral conversion to improve the efficiency of next-generation photovoltaics.
基金This work was financially supported by the Key R&D Program of Guangzhou(No.202007020003)National Natural Science Foundation of China(Nos.62122027,52002128,62075063,51772101,and 51872095)+2 种基金China Postdoctoral Science Foundation(Nos.2020M672621 and 2021M691054)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01X137)State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology(No.2020KF-19)。
文摘With the rapid growth of optical communications traffic,the demand for broadband optical amplifiers continues to increase.It is necessary to develop a gain medium that covers more optical communication bands.We precipitated PbS quantum dots(QDs) and Ba F_(2):Tm^(3+) nanocrystals (NCs) in the same glass to form two independent emission centers.The Ba F_(2)NCs in the glass can provide a crystal field environment with low phonon energy for rare earth (RE) ions and prevent the energy transfer between RE ions and PbS QDs.By adjusting the heat treatment schedule,the emission of the two luminescence centers from PbS QDs and Tm^(3+) ions perfectly splices and covers the ultra-broadband near-infrared emission from 1200 nm to 2000 nm with bandwidth over 430 nm.Therefore,it is expected to be a promising broadband gain medium for fiber amplifiers.
基金the National Natural Science Foundation of China(Grant No.59732040)
文摘The emission and excitation spectra of Gd2SiO5: Eu3+ were investigated using the VUVbeam line of the Beijing Synchrotron Radiation Facility (BSRF). The experimental results werediscussed in the frame of visible quantum cutting process involved in Gd3+-Eu3+ system. Upon di-rect excitation into the 6GJ states of Gd3+, two visible photon emissions from Eu3+ were observed.Cursory evaluation proved that Gd2SiO5: Eu3+ is an efficient visible quantum cutter.