Tuning of phosphor luminescence properties,including the emission energy/intensity and thermal stability,is an important way to develop superior luminescent materials for diverse applications.In this work,we discuss t...Tuning of phosphor luminescence properties,including the emission energy/intensity and thermal stability,is an important way to develop superior luminescent materials for diverse applications.In this work,we discuss the effect of band gap engineering and energy transfer on the luminescence properties of Ce^3+or Pr^3+doped(Y,Gd)AGG systems,and analyze the underlying reasons for their different phenomena.By using VUV-UV excitation spectra and constructing VRBE schemes,the changes of host band structure,5 d excited level energies and emission thermal stability of Ce^3+and Pr^3+with the incorporation of Gd^3+ions were studied.In addition,the energy transfer dynamics was also investigated in terms of the luminescence decay curves.This work demonstrates a way to tune phosphor luminescence properties by combining band gap engineering and energy transfer tailoring and provides an inspiring discussion on the different results of Ce^3+doping on the Ce^3+and Pr^3+emissions.展开更多
High-performance photodetectors hold promising potential in optical communication and imaging systems.However,conventional counterparts are suffering narrow detection range,high power consumption,and poor polarization...High-performance photodetectors hold promising potential in optical communication and imaging systems.However,conventional counterparts are suffering narrow detection range,high power consumption,and poor polarization sensitivity.Characteristics originating from switchable polarization in ferroelectrics can be used to optimize the photo-to-electric procedure and improve the photodetection performance.In this regard,we constructed a configuration by integrating 2-dimensional molybdenum disulfide(MoS_(2))with ferroelectric lithium niobate(LiNbO_(3)),resulting in the MoS_(2)/LiNbO_(3)heterostructured photodetector.Benefiting from the pyroelectric effect of LiNbO_(3),the limitation of bandgap on the detection range can be broken,thus broadening the response band of the detector to 365 to 1,064 nm,as well as enabling the self-powered characteristic.Meanwhile,high carrier mobility and decent light absorbance of MoS_(2)introduce robust light-matter interactions with the underlying LiNbO_(3),leading to ultrafast rise/fall times of≈150μs/250μs and switching ratios of up to≈190.Moreover,the highest responsivity,specific detectivity,and external quantum efficiency achieved were 17.3 A·W^(-1),4.3×10^(11)Jones,and 4,645.78%,respectively.Furthermore,because of the anisotropy of the spontaneous-polarized LiNbO_(3)substrate,the photocurrent of the device achieved a dichroic ratio of 7.42,comparing favorably to most MoS_(2)-based photodetectors.This work demonstrates the integration potential between ferroelectric LiNbO_(3)and 2-dimensional materials for high-performance photodetection.展开更多
Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstr...Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstrated that codoping with Y3＋ ions could efficiently improve the spectroscopic properties. Tm;Y：CaF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections, and much longer fluorescence lifetimes of the upper laser level（Tm3＋：3H4 level） than Tm：CaF2 crystals. Continuous-wave（CW） lasers around 1.97 μm were demonstrated in 4.0 at. % Tm,4.0 at. % Y：CaF2 single crystals under 792 nm laser diode（LD） pumping. The best laser performance has been demonstrated with a low threshold of 0.368 W, a high slope efficiency of 54.8%, and a maximum output power of 1.013 W.展开更多
基金Project supported by the National Natural Science Foundation of China(21671201,U1632101,61905289,11904425)Postdoctoral Science Foundation of China(2017M622846,2019M663202)。
文摘Tuning of phosphor luminescence properties,including the emission energy/intensity and thermal stability,is an important way to develop superior luminescent materials for diverse applications.In this work,we discuss the effect of band gap engineering and energy transfer on the luminescence properties of Ce^3+or Pr^3+doped(Y,Gd)AGG systems,and analyze the underlying reasons for their different phenomena.By using VUV-UV excitation spectra and constructing VRBE schemes,the changes of host band structure,5 d excited level energies and emission thermal stability of Ce^3+and Pr^3+with the incorporation of Gd^3+ions were studied.In addition,the energy transfer dynamics was also investigated in terms of the luminescence decay curves.This work demonstrates a way to tune phosphor luminescence properties by combining band gap engineering and energy transfer tailoring and provides an inspiring discussion on the different results of Ce^3+doping on the Ce^3+and Pr^3+emissions.
基金funded in part by the NSAF(U2030103,U2230111)the National Natural Science Foundation of China(61775084,62075088,and 12005210)+3 种基金the Youth Talent Support Programme of Guangdong Provincial Association for Science and Technology(SKXRC202304)the Natural Science Foundation of Guangdong Province(2020A1515010791,2021A0505030036,and 2022A1515110970)the Fundamental and application foundation project of Guangzhou(202201010654)the Fundamental Research Funds for the Central Universities(21622107 and 21622403).
文摘High-performance photodetectors hold promising potential in optical communication and imaging systems.However,conventional counterparts are suffering narrow detection range,high power consumption,and poor polarization sensitivity.Characteristics originating from switchable polarization in ferroelectrics can be used to optimize the photo-to-electric procedure and improve the photodetection performance.In this regard,we constructed a configuration by integrating 2-dimensional molybdenum disulfide(MoS_(2))with ferroelectric lithium niobate(LiNbO_(3)),resulting in the MoS_(2)/LiNbO_(3)heterostructured photodetector.Benefiting from the pyroelectric effect of LiNbO_(3),the limitation of bandgap on the detection range can be broken,thus broadening the response band of the detector to 365 to 1,064 nm,as well as enabling the self-powered characteristic.Meanwhile,high carrier mobility and decent light absorbance of MoS_(2)introduce robust light-matter interactions with the underlying LiNbO_(3),leading to ultrafast rise/fall times of≈150μs/250μs and switching ratios of up to≈190.Moreover,the highest responsivity,specific detectivity,and external quantum efficiency achieved were 17.3 A·W^(-1),4.3×10^(11)Jones,and 4,645.78%,respectively.Furthermore,because of the anisotropy of the spontaneous-polarized LiNbO_(3)substrate,the photocurrent of the device achieved a dichroic ratio of 7.42,comparing favorably to most MoS_(2)-based photodetectors.This work demonstrates the integration potential between ferroelectric LiNbO_(3)and 2-dimensional materials for high-performance photodetection.
基金financially supported by the National Natural Science Foundation of China(Nos.61422511,61635012,and 51432007)the Strategic Priority Program of the Chinese Academy of Sciences(No.XDB16030000)
文摘Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstrated that codoping with Y3＋ ions could efficiently improve the spectroscopic properties. Tm;Y：CaF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections, and much longer fluorescence lifetimes of the upper laser level（Tm3＋：3H4 level） than Tm：CaF2 crystals. Continuous-wave（CW） lasers around 1.97 μm were demonstrated in 4.0 at. % Tm,4.0 at. % Y：CaF2 single crystals under 792 nm laser diode（LD） pumping. The best laser performance has been demonstrated with a low threshold of 0.368 W, a high slope efficiency of 54.8%, and a maximum output power of 1.013 W.
