To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through...To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.展开更多
For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driv...For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.展开更多
Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. T...Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. The NIR-related luminescence is widely studied due to the excellent performance, such as good biocompatibility, deep tissue penetration depth, low self-fluorescence and minimal light damage to organisms. In this review, we mainly introduce the mechanism for rare earth up-conversion luminescence, NIR-Ⅱ luminescence and conclude their advantages compared with traditional luminescence.These excellent priorities provide the basis for NIR-related luminescence bioimaging in vivo. Additionally,we hilglight the scheme for the sensitive detection of substances in organisms and various methods for biological therapy. In spite of the existing research, it is outlined that NIR-related luminescence has great potential to be applied in different aspects, expanding perspectives and future challenges of research in related fields. Based on the current scientific achievements, this review can provide reference for research in the areas mentioned above, expand the research direction and arouse a broad interest in different disciplines to pay attention to rare earth luminescence.展开更多
In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The...In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping power.In addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay lifetimes.These results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.展开更多
High quality optical single crystals of cubic Yb_(2.96)Er_(0.04)Al_(5)O_(12)and Y_(2.96)Er_(0.04)A_(l5)O_(12)were successfully pre-pared using the OFZ method.The 980 nm photon absorption intensity by Yb_(2.96)Er_(0.04...High quality optical single crystals of cubic Yb_(2.96)Er_(0.04)Al_(5)O_(12)and Y_(2.96)Er_(0.04)A_(l5)O_(12)were successfully pre-pared using the OFZ method.The 980 nm photon absorption intensity by Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal is much larger than that in Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal,the transmission of Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal is lower than that of Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal,because the density of Yb_(2.96)Er_(0.04)Al_(5)O_(12)single crystal(6.604 g/cm^(3))is larger than that of Y_(2.96)Er_(0.04)A_(l5)O_(12)single crystal(4.529 g/cm^(3)).The up-conversion luminescence spec-tra of the crystals excited by 980 nm laser show several distinct groups of emission peaks at-544 and-556 nm,as well as-650 and-667 nm.The peak intensities of the up-conversion luminescence spec-trum for the Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal were much higher than those for the Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal.Over-all,the results of the present study suggest that Yb_(2.96)Er_(0.04)Al_(5)O_(12)single crystal may have advantages over Y_(2.96)Er_(0.04)A_(l5)O_(12)single crystal for luminescence in solid-state lasers.展开更多
Quantum dot-based up-conversion photodetector,in which an infrared photodiode(PD)and a quantum dot light-emitting diode(QLED)are back-to-back connected,is a promising candidate for low-cost infrared imaging.However,th...Quantum dot-based up-conversion photodetector,in which an infrared photodiode(PD)and a quantum dot light-emitting diode(QLED)are back-to-back connected,is a promising candidate for low-cost infrared imaging.However,the huge efficiency losses caused by integrating the PD and QLED together hasn’t been studied sufficiently.This work revealed at least three origins for the efficiency losses.First,the PD unit and QLED unit usually didn’t work under optimal conditions at the same time.Second,the potential barriers and traps at the interconnection between PD and QLED units induced unfavorable carrier recombination.Third,much emitted visible light was lost due to the strong visible absorption in the PD unit.Based on the understandings on the loss mechanisms,the infrared up-conversion photodetectors were optimized and achieved a breakthrough photon-to-photon conversion efficiency of 6.9%.This study provided valuable guidance on how to optimize the way of integration for up-conversion photodetectors.展开更多
The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of po...The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of power dependence of luminescence, which exhibited unusual behavior. Large hysteresis, as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.展开更多
A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used ...A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.展开更多
Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was deve...Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.展开更多
Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR...Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR)method complemented by detailed analysis on crystal structure,up-conversion luminescence and energy transfer from Yb^(3+)to Er^(3+).Upon 980 nm laser excitation,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors present525,547 and 659 nm emission bands assigned to the characteristic transitions of Er^(3+).Furthermore,Y_(4)GeO_(8):Er^(3+),Yb^(3+)samples show outstanding temperature sensing performances.To be specific,the minimal temperature resolution is 0.03 K(303 K),and the relative sensitivity of FIR can be up to 1.152%/K(303 K).Hence,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors can be possible candidates for thermometry devices.展开更多
Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+do...Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+doped CaLaAl3O7 phosphor was studied in detail.The two-photon process for the green emissions of Er^3+were confirmed by the power-dependent luminescence.The up-conversion optical temperature sensing performances of the Er^3+/Yb^3+-codoped CaLaAl3O7 phosphor were investigated based on the FIR technique.The maximum sensitivity of this phosphor can reach about 0.00345 K-1 at 453 K,which reveals this phosphor can be a promising candidate for optical thermometry devices.展开更多
The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosph...The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response. In this study, the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the near-infrared spectral range. The short circuit current （Isc）, open circuit voltage （Voc）, and conversion efficiency （η） of spectral conversion cells were measured. Preliminary experimental results revealed that the light conversion efficiency of a 1.5%–2.7% increase in Si-based cell was achieved.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 novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie...A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie acid （OA） and 1-0ctadeeene （ODE） with Y2（COa）3＇xH20, Er2（COa）3xH20, Na2CO3 and NH4F as precursors. This proposed method was simple and less toxic compared with generally used method so far. The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control ofNaYF4：Er NCs. The UC emission spectra were obtained with the emission wavelength at about 980 nm （4111/2--4115/2）, 800 nm （41912--415/2）, 660 nm （4F912--4115/2） and 540 nm （453/2----4115/2） from Er3＋ ions, by excitation wavelength of 1550 nm. The slope values, n, in the pump-power dependence, showed that the emission at 980 and 800 um were generated by 2-step UC and at 660 nm and 540 um were 3-step UC. The optical process for the UC excitation was discussed.展开更多
Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied ...Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.展开更多
yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 30...yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.展开更多
Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping...Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping during illumination is essentially required.Here we demonstrate the effect of detrapping on UCC dynamics by a rate equation approach.Accordingly,taking LaMgGa_(11)O_(19):Pr^(^(3+))phosphor as an example,we experimentally verified the dependence of illumination dose and duration on the thermoluminescence intensities using 450 nm laser excitation.The present model and experimental approach appear to be transferable to other phosphors,Thus,many existing persistent phosphors can now be revisited,paving the way toward advancing the understanding of UCC.展开更多
Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light c...Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.展开更多
A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upco...A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upconversion from terahertz wave to NIR laser was realized in a lithium niobate crystal.The minimum detectable terahertz energy of 9 p J was realized with the detection dynamic range of 54 d B,which was three orders of magnitude higher than that of commercial Golay cell.The detectable terahertz frequency range of the detection system was 0.90 Thz–1.83 THz.Besides,the effects of pump energy and effective gain length on the detection sensitivity were studied in experiment.The results showed that higher pump energy and longer effective gain length are helpful for improving the detection sensitivity of parametric up-conversion detector.展开更多
The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time ...The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.展开更多
基金supported by the National Natural Science Foundation of China(61865003)。
文摘To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.
基金Project supported by Hebei Province High-level Talent(Postdoctor)Funding Project(B2022003025)。
文摘For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.
基金Financial support from the National Natural Science Foundation of China(NSFC,Nos.51972076,52272144,22205048)the Heilongjiang Provincial Natural Science Foundation of China(No.JQ2022E001)+3 种基金the Natural Science Foundation of Shandong Province(No.ZR2020ZD42)Project funded by China Postdoctoral Science Foundation(No.2022M710931)the Fundamental Research Funds for the Central Universitiesthe Special Scientific Research Starting Foundation for Young teachers of Zhengzhou University(No.32213226).
文摘Rare earth luminescence has attracted widespread attention for several decades, among which nearinfrared(NIR) light-related up-conversion luminescence and NIR-Ⅱ luminescence are widely used in the biomedical field. The NIR-related luminescence is widely studied due to the excellent performance, such as good biocompatibility, deep tissue penetration depth, low self-fluorescence and minimal light damage to organisms. In this review, we mainly introduce the mechanism for rare earth up-conversion luminescence, NIR-Ⅱ luminescence and conclude their advantages compared with traditional luminescence.These excellent priorities provide the basis for NIR-related luminescence bioimaging in vivo. Additionally,we hilglight the scheme for the sensitive detection of substances in organisms and various methods for biological therapy. In spite of the existing research, it is outlined that NIR-related luminescence has great potential to be applied in different aspects, expanding perspectives and future challenges of research in related fields. Based on the current scientific achievements, this review can provide reference for research in the areas mentioned above, expand the research direction and arouse a broad interest in different disciplines to pay attention to rare earth luminescence.
基金Project supported by the National Natural Science Foundation of China(51202111)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation method.The crystal structure s and optical prope rties were investigated in detail.The intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping power.In addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay lifetimes.These results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.
基金supported by the National Natural Science Foundations of China(Nos.12175047 and 11975004)the Science and Technology Foundation of Guangxi University,China(No.2023BZXM003).
文摘High quality optical single crystals of cubic Yb_(2.96)Er_(0.04)Al_(5)O_(12)and Y_(2.96)Er_(0.04)A_(l5)O_(12)were successfully pre-pared using the OFZ method.The 980 nm photon absorption intensity by Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal is much larger than that in Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal,the transmission of Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal is lower than that of Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal,because the density of Yb_(2.96)Er_(0.04)Al_(5)O_(12)single crystal(6.604 g/cm^(3))is larger than that of Y_(2.96)Er_(0.04)A_(l5)O_(12)single crystal(4.529 g/cm^(3)).The up-conversion luminescence spec-tra of the crystals excited by 980 nm laser show several distinct groups of emission peaks at-544 and-556 nm,as well as-650 and-667 nm.The peak intensities of the up-conversion luminescence spec-trum for the Yb_(2.96)Er_(0.04)Al_(5)O_(12)crystal were much higher than those for the Y_(2.96)Er_(0.04)A_(l5)O_(12)crystal.Over-all,the results of the present study suggest that Yb_(2.96)Er_(0.04)Al_(5)O_(12)single crystal may have advantages over Y_(2.96)Er_(0.04)A_(l5)O_(12)single crystal for luminescence in solid-state lasers.
基金supported by the following research fundings including:the National Natural Science Foundation of China(Nos.62005114,62204078 and U22A2072)Natural Science Foundation of Henan-Excellent Youth Scholar(No.232300421092)Open Fund of the State Key Laboratory of Integrated Optoelectronics+(IOSKL2020KF01).
文摘Quantum dot-based up-conversion photodetector,in which an infrared photodiode(PD)and a quantum dot light-emitting diode(QLED)are back-to-back connected,is a promising candidate for low-cost infrared imaging.However,the huge efficiency losses caused by integrating the PD and QLED together hasn’t been studied sufficiently.This work revealed at least three origins for the efficiency losses.First,the PD unit and QLED unit usually didn’t work under optimal conditions at the same time.Second,the potential barriers and traps at the interconnection between PD and QLED units induced unfavorable carrier recombination.Third,much emitted visible light was lost due to the strong visible absorption in the PD unit.Based on the understandings on the loss mechanisms,the infrared up-conversion photodetectors were optimized and achieved a breakthrough photon-to-photon conversion efficiency of 6.9%.This study provided valuable guidance on how to optimize the way of integration for up-conversion photodetectors.
基金Project supported by Polish National Science Centre (N N507 584938,N N507599038)the Foundation for Polish Science
文摘The possibility of ttming between red, green and broadband white color of up-conversion was demonstrated in thermally 450 ℃ treated Yb/Er co-doped nano NaYF4 phosphor. The color variability was studied by means of power dependence of luminescence, which exhibited unusual behavior. Large hysteresis, as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.
文摘A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.
基金supported by the National Natural Science Foundation of China (50572029) Natural Science Foundation Project of Yunnan Province (2007E036M)
文摘Rare earth ions doped oxyfluoride glass with composition of 28SiO2·22AlO1.5·40PbF2·10PbO·（4.8-x） GdFy0.1NdF3.xYbF3·0.1TmF3 （x=-0, 0.1, 0.2, 0.5, 1, 2, 3, 4 and 4.8） in molar ratio was developed. When the oxyfluoride glasses were heat-treated at the first crystallization temperature, the glasses gave transparent glass-ceramics in which rare earth containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Compared with the glasses before heat treatment, the glass-ceramics exhibited very strong blue up-conversion luminescence under 800 nm light excitation. Rare earth containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass, the size of precipitated nanocrystals could be controlled by laser power and scan speed. The intensity of the blue up-conversion luminescence was strongly dependent on the precipitation of β-PbF2 nanocrystal and the YbF3 concentration. The reasons for the highly efficient Tm^3＋ up-conversion luminescence after laser irradiation were discussed.
基金Project supported by National Natural Science Foundation of China(11974315)Guangdong Science and Technology Innovation Strategy Foundation of China(20190310)。
文摘Herein,we reported novel Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors elaborated via conventional solid-state reaction.and we further explored their properties as optical thermometer by using fluorescence intensity ratio(FIR)method complemented by detailed analysis on crystal structure,up-conversion luminescence and energy transfer from Yb^(3+)to Er^(3+).Upon 980 nm laser excitation,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors present525,547 and 659 nm emission bands assigned to the characteristic transitions of Er^(3+).Furthermore,Y_(4)GeO_(8):Er^(3+),Yb^(3+)samples show outstanding temperature sensing performances.To be specific,the minimal temperature resolution is 0.03 K(303 K),and the relative sensitivity of FIR can be up to 1.152%/K(303 K).Hence,Y_(4)GeO_(8):Er^(3+),Yb^(3+)phosphors can be possible candidates for thermometry devices.
基金Project supported by National Natural Science Foundation of China(51802069,61205180)the First Batch of Young Talent Support Plan of Hebei ProvinceGraduate Student Innovation Project of Hebei University(hbu2018ss62)
文摘Herein,we reported Er^3+/Yb^3+co-doped CaLaAl3O7 up-conversion phosphors synthesized via solid state reaction,which was further explored as a new optical thermometry.The luminescent properties of Er^3+or Er^3+/Yb^3+doped CaLaAl3O7 phosphor was studied in detail.The two-photon process for the green emissions of Er^3+were confirmed by the power-dependent luminescence.The up-conversion optical temperature sensing performances of the Er^3+/Yb^3+-codoped CaLaAl3O7 phosphor were investigated based on the FIR technique.The maximum sensitivity of this phosphor can reach about 0.00345 K-1 at 453 K,which reveals this phosphor can be a promising candidate for optical thermometry devices.
基金Project supported by National Science Council of Taiwan (NSC98-2113-M-009-005-MY3)
文摘The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response. In this study, the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the near-infrared spectral range. The short circuit current （Isc）, open circuit voltage （Voc）, and conversion efficiency （η） of spectral conversion cells were measured. Preliminary experimental results revealed that the light conversion efficiency of a 1.5%–2.7% increase in Si-based cell was achieved.
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.
文摘A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie acid （OA） and 1-0ctadeeene （ODE） with Y2（COa）3＇xH20, Er2（COa）3xH20, Na2CO3 and NH4F as precursors. This proposed method was simple and less toxic compared with generally used method so far. The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control ofNaYF4：Er NCs. The UC emission spectra were obtained with the emission wavelength at about 980 nm （4111/2--4115/2）, 800 nm （41912--415/2）, 660 nm （4F912--4115/2） and 540 nm （453/2----4115/2） from Er3＋ ions, by excitation wavelength of 1550 nm. The slope values, n, in the pump-power dependence, showed that the emission at 980 and 800 um were generated by 2-step UC and at 660 nm and 540 um were 3-step UC. The optical process for the UC excitation was discussed.
文摘Er3 +/Yb3 +-codoped oxyfluoride crystallite glass was prepared with melting technique. The compositions and the melting temperature and the annealing temperature of the rare earth-doped crystallite glass were studied in detail. The emission spectra of samples were measured with the Hitachi F-4500 fluorescent photometer pumped by 980 nm wavelength laser. The up-conversion luminescence mechanism was illuminated on the view of the photophysics. By measuring the relationship between luminescent intensity and pump power, it is confirmed that the emission peaks at 550 nm belong to two-photon process, while that at 665 nm belongs to three-photon process. Moreover, the distributions of crystalline were determined by SEM.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10804015 )the Science Foundation of the Education Department of Liaoning Province of China (Grant No. 2009A417)
文摘yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.
基金Project supported by the National Natural Science Foundation of China(11774046)the Department of Science and Technology of Jilin Province(20180414082 GH)。
文摘Up-conversion charging(UCC)is a promising approach for charging storage phosphors using low-energy excitation light sources.For further understanding the UCC,research on the competition between trapping and detrapping during illumination is essentially required.Here we demonstrate the effect of detrapping on UCC dynamics by a rate equation approach.Accordingly,taking LaMgGa_(11)O_(19):Pr^(^(3+))phosphor as an example,we experimentally verified the dependence of illumination dose and duration on the thermoluminescence intensities using 450 nm laser excitation.The present model and experimental approach appear to be transferable to other phosphors,Thus,many existing persistent phosphors can now be revisited,paving the way toward advancing the understanding of UCC.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92065101 and 11934013)Anhui Initiative In Quantum Information Technologies(Grant No.AHY020200)。
文摘Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1837202,61775160,61771332,62011540006,and 62175182)。
文摘A high-sensitive terahertz detector operating at room temperature was demonstrated based on parametric upconversion.A nanosecond 1064-nm Nd:YAG laser was used to pump the parametric up-conversion detector and the upconversion from terahertz wave to NIR laser was realized in a lithium niobate crystal.The minimum detectable terahertz energy of 9 p J was realized with the detection dynamic range of 54 d B,which was three orders of magnitude higher than that of commercial Golay cell.The detectable terahertz frequency range of the detection system was 0.90 Thz–1.83 THz.Besides,the effects of pump energy and effective gain length on the detection sensitivity were studied in experiment.The results showed that higher pump energy and longer effective gain length are helpful for improving the detection sensitivity of parametric up-conversion detector.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074003 and 20973001)the Key Program of Educational Commission of Anhui Province of China (Grant No. KJ2010A132)
文摘The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.
