High-density germanate glasses doped with Tb^(3+)ions were synthesized via the melt-quenching meth-od.The physical and luminescent properties of these glasses were characterized through various techniques,in-cluding d...High-density germanate glasses doped with Tb^(3+)ions were synthesized via the melt-quenching meth-od.The physical and luminescent properties of these glasses were characterized through various techniques,in-cluding density measurement,differential scanning calorimetry(DSC),photoluminescence(PL)spectroscopy,X-ray excited luminescence(XEL)spectroscopy,and fluorescence decay analysis.The densities of the germanate glasses were greater than 6.1 g/cm^(3).Upon excitations of ultraviolet(UV)light and X-rays,the glasses emitted in-tense green emissions.The fluorescence lifetime of the strongest emission peak at 544 nm,measured under 377 nm excitation,ranged from 1.52 ms to 1.32 ms.In the glass specimens,the maximum XEL integral intensity reached roughly 26%of that of the commercially available Bi_(4)Ge_(3)O_(12)(BGO)crystal.These results indicate that Tb^(3+)-doped high-density germanate scintillating glasses hold potential as scintillation materials for X-ray imaging applications.展开更多
A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100...A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100-mW stable continuous-wave single transverse and longitudinal mode lasing at 195Ohm are achieved. The measured relative intensity noise is less than -135dB/Hz at frequencies over 5 MHz. The signal-to-noise ratio of the laser is larger than 72dB, and the laser linewidth is less than 6kHz, while the obtained linear polarization extinction ratio is higher than 22 dB.展开更多
We report the observation of bubble generation and migration in a germanate g/ass during irradiation by a femtosecond laser of high repetition rate. Bubbles are formed around the focal area of the laser beam, and thei...We report the observation of bubble generation and migration in a germanate g/ass during irradiation by a femtosecond laser of high repetition rate. Bubbles are formed around the focal area of the laser beam, and their movement indicates the presence of thermal gravity convection in the glass melt, which is beyond the existing theoretical model about temperature l^eld of focal area. Inside the bubbles, oxygen molecules are observed by the con focal Raman micro-spectroscopy. The generation of molecular oxygen and bubbles is explained in terms of the spatial separation of Ge and 0 ions and micro-explosion inside the glass melt.展开更多
Two tetravalent uranium silicate and germanate M_(2)U^(Ⅳ)T_(3)O_(9)(M=K,Cs;T=Si,Ge)crystals were crystalized under inert gas by molten salt flux growth method.K_(2)USi_(3)O_(9)(1)crystallizes in the monoclinic space ...Two tetravalent uranium silicate and germanate M_(2)U^(Ⅳ)T_(3)O_(9)(M=K,Cs;T=Si,Ge)crystals were crystalized under inert gas by molten salt flux growth method.K_(2)USi_(3)O_(9)(1)crystallizes in the monoclinic space group P1_(21)/n1 with lattice parameters a=7.1076?,b=10.4776?,c=12.2957?,γ=120°and V=915.67?^(3).Cs_(2)UGe_(3)O_(9)(2)crystallizes in a hexagonal space group P-6 with lattice constants of a=7.5138?,b=7.5138?,c=11.0114?,γ=120°and V=538.38?^(3).Bond valence calculations indicate tetravalent uranium in both structures,which contain three-membered single-ring T_(3)O_(9)^(6-) trimers.K_(2)USi_(3)O_(9) is the first uranium silicate that contains the Si_(3)O_(9)^(6-) trimers.展开更多
Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-section...Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.展开更多
Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion ...Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion in doped samples,formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after g-ray irradiation are inhibited.Thereby,Nb_(2)O_(5)dopant can enhance radiation resistance of BGG glass,and 1.0%Nb2O5 concentration is the best.展开更多
The germanate glass ceramics is a potential candidate material for infrared （IR） dome and window applications. The crystallization mechanism of 20BaO-10Ga2O3-70GeO2 glass was investigated by differential thermal ana...The germanate glass ceramics is a potential candidate material for infrared （IR） dome and window applications. The crystallization mechanism of 20BaO-10Ga2O3-70GeO2 glass was investigated by differential thermal analysis （DTA）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Two different types of phase evolution were found in the early stage of crystallization： （1） the further growth of the microcrystal formed during the slow cooling of glass melt and （2） the glass-in-glass phase separation. The controlled crystatlization was obtained by two-step heat treatment. obtained, with expected thermal and mechanical The middle infrared （MIR）-transparent glass ceramics were improvements.展开更多
A layered zirconogermanate, （H2DETA）[ZrGe3O8F2]（1）, was hydro（solvo）thermally synthesized with diethylenetriamine（DETA） as template, and structurally determined by X-ray single-crystal diffraction. Compound 1 ...A layered zirconogermanate, （H2DETA）[ZrGe3O8F2]（1）, was hydro（solvo）thermally synthesized with diethylenetriamine（DETA） as template, and structurally determined by X-ray single-crystal diffraction. Compound 1 crystallized in the monoclinic space group P21/c with data of unit cell： a=0.7644（2） nm, b=1.1235（2） nm, c=1.6860（3） nm, V=1.4479（5） nm^3,/a（Mo Ka）=6.931 mm^-1, Z=4, R1=0.0402 for 3236 reflections with Fo〉2σ（Fo）. The structure of compound I was formed by alternatively packing the inorganic layer of ZrGe3O8F2 and H2DETA templated molecules along （001） direction. It was worth pointing out that the odd bifurcated 7MR nets were surrounded by odd 3MR. The protonated and disordered H2DETA cations not only balanced the superfluous charges of framework but also stabilized the structure of compound 1 by the hydrogen bond between -NH3 group and oxygen on the framework. Furthermore, IR and TG were utilized to characterize the structure and thermal stability, respectively.展开更多
A novel gallium germanate (83/2 Na2O . 1/2 Ga2O3 . 24 GeO2) was synthsized by a sol-gel method and hydrothermal crystallization. The germanate was characterized with scanning electron microscopy, electronic energy spe...A novel gallium germanate (83/2 Na2O . 1/2 Ga2O3 . 24 GeO2) was synthsized by a sol-gel method and hydrothermal crystallization. The germanate was characterized with scanning electron microscopy, electronic energy spectrum, inductively couple plasma-emission spectrum and powder X-ray diffraction. The properties of crystal appearance, size, thermal stability and melting point were studied as well as some influence factors on synthesis process.展开更多
A novel indium germanate (183/2Na 2O·1/2In 2O 3·28GeO 2) was synthesized by a sol gel and hydrothermal crystallization. The germanate was characterized with scanning electronic microscopy, electronic en...A novel indium germanate (183/2Na 2O·1/2In 2O 3·28GeO 2) was synthesized by a sol gel and hydrothermal crystallization. The germanate was characterized with scanning electronic microscopy, electronic energy spectrum, inductively couple plasma emission spectrum and powder X ray diffraction. The properties on its crystal appearance, size, thermal stability and melting point, and some influent factors on synthesis were studied.展开更多
Emission enhancement at 2.7 μm is observed in Er^3＋/Pr^3＋--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient ene...Emission enhancement at 2.7 μm is observed in Er^3＋/Pr^3＋--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3＋ and Pr^3＋; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3＋/Pr^3＋- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3＋/Pr^3＋-codoped germanate glass can be used to achieve efficient 2.7-μm emission.展开更多
Bismuth(Bi)-doped near-infared(NIR)glass that can cover the entire optical communication window(850,1310,and1550 nm)has become the subject of extensive research for developing photonic devices,particularly,tunable fib...Bismuth(Bi)-doped near-infared(NIR)glass that can cover the entire optical communication window(850,1310,and1550 nm)has become the subject of extensive research for developing photonic devices,particularly,tunable fiber lasers and ultrabroadband optical amplifiers.However,the realization of highly efficient NIR luminescence from Bi-doped glass is still full of challenges.Notably,due to the co-existence of multiple Bi NIR centers in the glass,the origin of newly generated Bi NIR emission peaks at~930 and~1520 nm is still controversial.Here,we report a new Bi-doped nitridated germanate glass with tunable ultrabroadband NIR emission(850–1700 nm)and high external quantum efficiency(EQE)of~50%.A series of studies,including spectral analysis,nuclear magnetic resonance(NMR),and others,provide powerful evidence for the mechanism of luminescence enhancement and tunability,and make reasonable inferences about the origin of the new emission bands at~930 and~1520 nm.We believe that the results discussed above would enrich our understanding about multiple Bi NIR emission behaviors and contribute to the design and fabrication of highly efficient Bi-doped ultrabroadband wavelength-tunable optical glass fiber amplifiers and lasers in the future.展开更多
Bismuth （Bi）-doped laser glasses and fiber devices have aroused wide attentions due to their unique potential to work in the new spectral range of 1 to 1.8 μm traditional laser ions, such as rare earth, cannot reac...Bismuth （Bi）-doped laser glasses and fiber devices have aroused wide attentions due to their unique potential to work in the new spectral range of 1 to 1.8 μm traditional laser ions, such as rare earth, cannot reach. Current Bi-dopcd silica glass fibers have to be made by modified chemical vapor deposition at a temperature higher than 2000℃. This unavoidably leads to the tremendous loss of Bi by evaporation, since the temperature is several hundred degrees Celsius higher than the Bi boiling temperature, and, therefore, trace Bi （-50 ppm） resides within the final product of silica fiber. So, the gain of such fiber is usually extremely low. One of the solutions is to make the fibers at a temperature much lower than the boiling temperature of Bi. The challenge for this is to find a lower melting point glass, which can stabilize Bi in the near infrared emission center and, meanwhile, does not lose glass transparency during fiber fabrication. None of previously reported Bi-doped multicomponent glasses can meet the prerequisite. Here, we, after hundreds of trials on optimization over glass components, activator content, melting temperature, etc., find a novel Bi-doped gallogermanate glass, which shows good tolerance to thermal impact and can accommodate a higher content of Bi. Consequently, we successfully manu- facture the germanate fiber by a rod-in-tube technique at 850℃. The fiber exhibits similar luminescence to the bulk glass, and it shows saturated absorption at 808 nm rather than 980 nm as the incident power becomes higher than 4 W. Amplified spontaneous emissions are observed upon the pumps of either 980 or 1064 nm from ger- manate fiber.展开更多
We report a ring cavity passively harmonic mode-locked fiber laser using a newly developed thulium- bismuth co-doped fiber （TBF） as a gain medium in conjunction with a carbon nanotube （CNT）-based saturable absorbe...We report a ring cavity passively harmonic mode-locked fiber laser using a newly developed thulium- bismuth co-doped fiber （TBF） as a gain medium in conjunction with a carbon nanotube （CNT）-based saturable absorber. The TBF laser generates a third harmonic mode-locked soliton pulse train with a high repetition rate of 50 MHz and a pulse duration of 1.86 ps. The laser operates at 1 901.6 nm with an average power of 6.6 mW, corresponding to a pulse energy of 0.132 nJ, at a 1 552 nm pump power of 723.3 roW.展开更多
On 28 November 2024,the Chinese Association for International Understanding(CAFIU)hosted the Dialogue on Mutual Learning between Chinese and German Civilisations in Berlin,Germany.Ji Bingxuan,Vice-Chairperson of the S...On 28 November 2024,the Chinese Association for International Understanding(CAFIU)hosted the Dialogue on Mutual Learning between Chinese and German Civilisations in Berlin,Germany.Ji Bingxuan,Vice-Chairperson of the Standing Committee of the 13th National People's Congress of China and President of CAFIU,who was on a visit in Germany,attended the Dialogue and delivered a keynote speech.展开更多
This study explores the application of Production-Oriented Approach(POA)in teaching German to nursing students in colleges and universities.Focusing on the requirements of the German B1 exam,the study takes the themat...This study explores the application of Production-Oriented Approach(POA)in teaching German to nursing students in colleges and universities.Focusing on the requirements of the German B1 exam,the study takes the thematic unit of“Movement”as an example,and designs the teaching through the links of“drive-enable-evaluate”.The results show that POA effectively improves students’speaking and writing output,but there are still deficiencies in reading and listening.Accordingly,this study has proposed the strategies of“vocabulary in-depth facilitation”and“accurate matching of listening and writing”to optimize the input materials and skills training,achieve the goal of“learning and using”,and provide a practical path for teaching German for Special Purposes.This provides a practical path for the teaching of German for special purposes.展开更多
AT No.1 Xiaofenqiao,Guangzhou Road,Nanjing,a grey-brick Western-style villa stands quietly in the green shade of dense plane trees.When the breeze stirs the leaves,they rustle as if whispering old stories.The two-stor...AT No.1 Xiaofenqiao,Guangzhou Road,Nanjing,a grey-brick Western-style villa stands quietly in the green shade of dense plane trees.When the breeze stirs the leaves,they rustle as if whispering old stories.The two-story house was the former residence of John Rabe(1882-1950),representative of German Siemens China Co.in Nanjing.展开更多
The full potential of advanced coating and finishingtechnologies for the production of technical textiles willbe outlined by Monforts specialists at Techtextil NorthAmerica which takes place in Atlanta,Georgia,from Ma...The full potential of advanced coating and finishingtechnologies for the production of technical textiles willbe outlined by Monforts specialists at Techtextil NorthAmerica which takes place in Atlanta,Georgia,from May6-8.The company and its US representative PSP Market-ing,of Charlotte,North Carolina,will be part of the exten-sive VDMA German Pavilion at the show,at stand 323lwithin the Georgia World Congress Center.展开更多
文摘High-density germanate glasses doped with Tb^(3+)ions were synthesized via the melt-quenching meth-od.The physical and luminescent properties of these glasses were characterized through various techniques,in-cluding density measurement,differential scanning calorimetry(DSC),photoluminescence(PL)spectroscopy,X-ray excited luminescence(XEL)spectroscopy,and fluorescence decay analysis.The densities of the germanate glasses were greater than 6.1 g/cm^(3).Upon excitations of ultraviolet(UV)light and X-rays,the glasses emitted in-tense green emissions.The fluorescence lifetime of the strongest emission peak at 544 nm,measured under 377 nm excitation,ranged from 1.52 ms to 1.32 ms.In the glass specimens,the maximum XEL integral intensity reached roughly 26%of that of the commercially available Bi_(4)Ge_(3)O_(12)(BGO)crystal.These results indicate that Tb^(3+)-doped high-density germanate scintillating glasses hold potential as scintillation materials for X-ray imaging applications.
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2013AA031502 and 2014AA041902the National Natural Science Foundation of China under Grant Nos 11174085,51132004,and 51302086+3 种基金the Natural Science Foundation of Guangdong Province under Grant Nos S2011030001349 and S20120011380the China National Funds for Distinguished Young Scientists under Grant No 61325024the Science and Technology Project of Guangdong Province under Grant No 2013B090500028the ’Cross and Cooperative’ Science and Technology Innovation Team Project of Chinese Academy of Sciences under Grant No 2012-119
文摘A compact linearly polarized, low-noise, narrow-linewidth, single-frequency fiber laser at 1950nm is demonstrated. This compact fiber laser is based on a 21-mm-long homemade Tm3＋-doped germanate glass fiber. Over 100-mW stable continuous-wave single transverse and longitudinal mode lasing at 195Ohm are achieved. The measured relative intensity noise is less than -135dB/Hz at frequencies over 5 MHz. The signal-to-noise ratio of the laser is larger than 72dB, and the laser linewidth is less than 6kHz, while the obtained linear polarization extinction ratio is higher than 22 dB.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51132004 and 61475047the National Basic Research Program of China under Grant No 2011CB808100+2 种基金the Natural Science Foundation of Guangdong Province under Grant No S2011030001349the Fundamental Research Funds for the Central Universities under Grant No 2013ZM0001the Open Fund of the State Key Laboratory of High Field Laser Physics of Shanghai Institute of Optics and Fine Mechanics
文摘We report the observation of bubble generation and migration in a germanate g/ass during irradiation by a femtosecond laser of high repetition rate. Bubbles are formed around the focal area of the laser beam, and their movement indicates the presence of thermal gravity convection in the glass melt, which is beyond the existing theoretical model about temperature l^eld of focal area. Inside the bubbles, oxygen molecules are observed by the con focal Raman micro-spectroscopy. The generation of molecular oxygen and bubbles is explained in terms of the spatial separation of Ge and 0 ions and micro-explosion inside the glass melt.
基金supported by the National Science Fund for Young Scholars(No.22106165)the National Science Fund for Distinguished Young Scholars(No.21925603)+1 种基金the Major Program of the National Natural Science Foundation of China(No.21790373)the National Natural Science Foundation of China(No.U20B2020)。
文摘Two tetravalent uranium silicate and germanate M_(2)U^(Ⅳ)T_(3)O_(9)(M=K,Cs;T=Si,Ge)crystals were crystalized under inert gas by molten salt flux growth method.K_(2)USi_(3)O_(9)(1)crystallizes in the monoclinic space group P1_(21)/n1 with lattice parameters a=7.1076?,b=10.4776?,c=12.2957?,γ=120°and V=915.67?^(3).Cs_(2)UGe_(3)O_(9)(2)crystallizes in a hexagonal space group P-6 with lattice constants of a=7.5138?,b=7.5138?,c=11.0114?,γ=120°and V=538.38?^(3).Bond valence calculations indicate tetravalent uranium in both structures,which contain three-membered single-ring T_(3)O_(9)^(6-) trimers.K_(2)USi_(3)O_(9) is the first uranium silicate that contains the Si_(3)O_(9)^(6-) trimers.
基金supported by the National Natural Science Foundation of China (Grant 60777030)the Open Foundation of the Key Laboratory of Ningbo City (2007A22010) K.C.Wong Magna Fund in Ningbo University
文摘Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.
基金supported by China National Funds for Guangdong Key Research and Development Program(Grant No.2018B090904001)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(Grant No.2017BT01X137)+2 种基金Key Laboratory of Laser Device Technology Foundation of China Ordnance Industry Group Co.(Grant No.KLLDT202010)the Key R&D Program of Guangzhou(Grant No.202007020003)the National Natural Science Foundation of China(Grant No.52002131)。
文摘Effects of Nb_(2)O_(5)dopant on the radiation response of barium gallo-germanate(BGG)glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy.Owing to the Nb^(5+)$Nb^(3+)interconversion in doped samples,formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after g-ray irradiation are inhibited.Thereby,Nb_(2)O_(5)dopant can enhance radiation resistance of BGG glass,and 1.0%Nb2O5 concentration is the best.
基金supports from Shanghai Pujiang Program and the Hundred of Talents Pragram of Chinese Academy of Sciences are gratefully acknowledged
文摘The germanate glass ceramics is a potential candidate material for infrared （IR） dome and window applications. The crystallization mechanism of 20BaO-10Ga2O3-70GeO2 glass was investigated by differential thermal analysis （DTA）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Two different types of phase evolution were found in the early stage of crystallization： （1） the further growth of the microcrystal formed during the slow cooling of glass melt and （2） the glass-in-glass phase separation. The controlled crystatlization was obtained by two-step heat treatment. obtained, with expected thermal and mechanical The middle infrared （MIR）-transparent glass ceramics were improvements.
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars(No.20071108)the National Natural Science Foundation of China(No.20701023)
文摘A layered zirconogermanate, （H2DETA）[ZrGe3O8F2]（1）, was hydro（solvo）thermally synthesized with diethylenetriamine（DETA） as template, and structurally determined by X-ray single-crystal diffraction. Compound 1 crystallized in the monoclinic space group P21/c with data of unit cell： a=0.7644（2） nm, b=1.1235（2） nm, c=1.6860（3） nm, V=1.4479（5） nm^3,/a（Mo Ka）=6.931 mm^-1, Z=4, R1=0.0402 for 3236 reflections with Fo〉2σ（Fo）. The structure of compound I was formed by alternatively packing the inorganic layer of ZrGe3O8F2 and H2DETA templated molecules along （001） direction. It was worth pointing out that the odd bifurcated 7MR nets were surrounded by odd 3MR. The protonated and disordered H2DETA cations not only balanced the superfluous charges of framework but also stabilized the structure of compound 1 by the hydrogen bond between -NH3 group and oxygen on the framework. Furthermore, IR and TG were utilized to characterize the structure and thermal stability, respectively.
文摘A novel gallium germanate (83/2 Na2O . 1/2 Ga2O3 . 24 GeO2) was synthsized by a sol-gel method and hydrothermal crystallization. The germanate was characterized with scanning electron microscopy, electronic energy spectrum, inductively couple plasma-emission spectrum and powder X-ray diffraction. The properties of crystal appearance, size, thermal stability and melting point were studied as well as some influence factors on synthesis process.
文摘A novel indium germanate (183/2Na 2O·1/2In 2O 3·28GeO 2) was synthesized by a sol gel and hydrothermal crystallization. The germanate was characterized with scanning electronic microscopy, electronic energy spectrum, inductively couple plasma emission spectrum and powder X ray diffraction. The properties on its crystal appearance, size, thermal stability and melting point, and some influent factors on synthesis were studied.
基金supported by the National Natural Science Foundation of China(Nos.51172252 and 61177083)
文摘Emission enhancement at 2.7 μm is observed in Er^3＋/Pr^3＋--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3＋ and Pr^3＋; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3＋/Pr^3＋- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3＋/Pr^3＋-codoped germanate glass can be used to achieve efficient 2.7-μm emission.
基金supported by the National Key R&D Program of China(No.2021YFB2800500)the Research Program of Zhejiang Lab(No.113014-AC2101)+1 种基金the National Natural Science Foundation of China(Nos.51872095,U20A20211,and 62105297)the Zhejiang Provincial Natural Science Foundation(Nos.LQ22A040011 and LZ23F050002)。
文摘Bismuth(Bi)-doped near-infared(NIR)glass that can cover the entire optical communication window(850,1310,and1550 nm)has become the subject of extensive research for developing photonic devices,particularly,tunable fiber lasers and ultrabroadband optical amplifiers.However,the realization of highly efficient NIR luminescence from Bi-doped glass is still full of challenges.Notably,due to the co-existence of multiple Bi NIR centers in the glass,the origin of newly generated Bi NIR emission peaks at~930 and~1520 nm is still controversial.Here,we report a new Bi-doped nitridated germanate glass with tunable ultrabroadband NIR emission(850–1700 nm)and high external quantum efficiency(EQE)of~50%.A series of studies,including spectral analysis,nuclear magnetic resonance(NMR),and others,provide powerful evidence for the mechanism of luminescence enhancement and tunability,and make reasonable inferences about the origin of the new emission bands at~930 and~1520 nm.We believe that the results discussed above would enrich our understanding about multiple Bi NIR emission behaviors and contribute to the design and fabrication of highly efficient Bi-doped ultrabroadband wavelength-tunable optical glass fiber amplifiers and lasers in the future.
基金supported by the National Key Research and Development Plan(No.2017YFF0104504)the National Natural Science Foundation of China(Nos.51672085 and 51322208)+2 种基金the Program for Innovative Research Team in University of Ministry of Education of China(No.IRT_17R38)the Key Program of Guangzhou Scientific Research Special Project(No.201607020009)the Fundamental Research Funds for the Central Universities
文摘Bismuth （Bi）-doped laser glasses and fiber devices have aroused wide attentions due to their unique potential to work in the new spectral range of 1 to 1.8 μm traditional laser ions, such as rare earth, cannot reach. Current Bi-dopcd silica glass fibers have to be made by modified chemical vapor deposition at a temperature higher than 2000℃. This unavoidably leads to the tremendous loss of Bi by evaporation, since the temperature is several hundred degrees Celsius higher than the Bi boiling temperature, and, therefore, trace Bi （-50 ppm） resides within the final product of silica fiber. So, the gain of such fiber is usually extremely low. One of the solutions is to make the fibers at a temperature much lower than the boiling temperature of Bi. The challenge for this is to find a lower melting point glass, which can stabilize Bi in the near infrared emission center and, meanwhile, does not lose glass transparency during fiber fabrication. None of previously reported Bi-doped multicomponent glasses can meet the prerequisite. Here, we, after hundreds of trials on optimization over glass components, activator content, melting temperature, etc., find a novel Bi-doped gallogermanate glass, which shows good tolerance to thermal impact and can accommodate a higher content of Bi. Consequently, we successfully manu- facture the germanate fiber by a rod-in-tube technique at 850℃. The fiber exhibits similar luminescence to the bulk glass, and it shows saturated absorption at 808 nm rather than 980 nm as the incident power becomes higher than 4 W. Amplified spontaneous emissions are observed upon the pumps of either 980 or 1064 nm from ger- manate fiber.
基金supported by Ministry of Higher Education (MOHE) under the Exploratory Research GrantScheme (ERGS) (No. ER012-2012A)the University of Malaya under a Pangurusan Penyelidikan Pascasiswazah (PPP) Grant (No. PV030/2012A)
文摘We report a ring cavity passively harmonic mode-locked fiber laser using a newly developed thulium- bismuth co-doped fiber （TBF） as a gain medium in conjunction with a carbon nanotube （CNT）-based saturable absorber. The TBF laser generates a third harmonic mode-locked soliton pulse train with a high repetition rate of 50 MHz and a pulse duration of 1.86 ps. The laser operates at 1 901.6 nm with an average power of 6.6 mW, corresponding to a pulse energy of 0.132 nJ, at a 1 552 nm pump power of 723.3 roW.
文摘On 28 November 2024,the Chinese Association for International Understanding(CAFIU)hosted the Dialogue on Mutual Learning between Chinese and German Civilisations in Berlin,Germany.Ji Bingxuan,Vice-Chairperson of the Standing Committee of the 13th National People's Congress of China and President of CAFIU,who was on a visit in Germany,attended the Dialogue and delivered a keynote speech.
文摘This study explores the application of Production-Oriented Approach(POA)in teaching German to nursing students in colleges and universities.Focusing on the requirements of the German B1 exam,the study takes the thematic unit of“Movement”as an example,and designs the teaching through the links of“drive-enable-evaluate”.The results show that POA effectively improves students’speaking and writing output,but there are still deficiencies in reading and listening.Accordingly,this study has proposed the strategies of“vocabulary in-depth facilitation”and“accurate matching of listening and writing”to optimize the input materials and skills training,achieve the goal of“learning and using”,and provide a practical path for teaching German for Special Purposes.This provides a practical path for the teaching of German for special purposes.
文摘AT No.1 Xiaofenqiao,Guangzhou Road,Nanjing,a grey-brick Western-style villa stands quietly in the green shade of dense plane trees.When the breeze stirs the leaves,they rustle as if whispering old stories.The two-story house was the former residence of John Rabe(1882-1950),representative of German Siemens China Co.in Nanjing.
文摘The full potential of advanced coating and finishingtechnologies for the production of technical textiles willbe outlined by Monforts specialists at Techtextil NorthAmerica which takes place in Atlanta,Georgia,from May6-8.The company and its US representative PSP Market-ing,of Charlotte,North Carolina,will be part of the exten-sive VDMA German Pavilion at the show,at stand 323lwithin the Georgia World Congress Center.
