The growth of LiNbO3 single crystal with Er^3＋ and Zn^2＋ co-doped using Bridgman method and its characteristic absorption spectra and fluorescence spectra were reported. Large-size crystals initially containing Zn^2...The growth of LiNbO3 single crystal with Er^3＋ and Zn^2＋ co-doped using Bridgman method and its characteristic absorption spectra and fluorescence spectra were reported. Large-size crystals initially containing Zn^2＋ （3%） and Er^3＋ （0.6%） with good optical quality were obtained using optimized conditions such as a growth rate of 0.8- 1.5 mm·h^-1 and a temperature gradient of about 30 - 35℃·cm^-1 across the solid-liquid interface and the sealed platinum crucible. X-ray diffraction and differential thermal analysis （DTA） were used to characterize the crystals. The results indicate that the concentration of Er^3＋ ions in crystals, their absorption intensity, and their fluorescence intensity decrease from the bottom to the top in the crystals. However, for the upper part of the crystal, the up-conversion fluorescence intensity is higher than that of the lower part excited by an 800 or 970 nm pump. The effects of the crystal lattice, their structural defect and their effective segregation of Er^3＋ ions were discussed with respect to the variations of the up-conversion fluorescence intensity.展开更多
Photorefractive properties of Hf：Fe：LiNbO3 crystals with various [Li]/[Nb] ratios have been investigated at 488 nm wavelength based on the two-wave coupling experiment. High diffraction efficiency and large recordin...Photorefractive properties of Hf：Fe：LiNbO3 crystals with various [Li]/[Nb] ratios have been investigated at 488 nm wavelength based on the two-wave coupling experiment. High diffraction efficiency and large recording sensitivity are observed and explained. The decrease in Li vacancies is suggested to be the main contributor to the increase in the photoconductivity and subsequently to the induction of the improvement of recording sensitivity. The saturation diffraction efficiency is measured up to 80.2%, and simultaneously the recording sensitivity of 0.91 cm/J is achieved to in the Hf：Fe：LiNbO3 crystal grown from the melt with the [Li]/[Nb] ratio of 1.20, which is significantly enhanced as compared with those of the Hf：Fe：LiNbO3 crystal with the [Li]/[Nb] ratio of 0.94 in melt under the same experimental conditions. Experimental results definitely show that increasing the [Li]/[Nb] ratio in crystal is an effective method＇for Hf：Fe：LiNbO3 crystal to improve its photorefractive properties.展开更多
The growth of LiNbO3 single crystal with Er^3＋/Zn^2＋ co-doped by the bridgman method and the characteristics of absorption spectra and fluorescence spectra were reported. By means of the optimized con- ditions such ...The growth of LiNbO3 single crystal with Er^3＋/Zn^2＋ co-doped by the bridgman method and the characteristics of absorption spectra and fluorescence spectra were reported. By means of the optimized con- ditions such as growth rate of 0.8 - 1.5 mm · h^- 1, temperature gradient about 30 - 35℃ ·cm^-1 across the solid-liquid interface and sealed platinum, large size crystals containing Zn^2＋ （3%） and Er^3＋ （0.6%） with good optical quality were obtained. X-ray diffraction and DTA were used to characterize the crystals. The results indicate that the concentration of Er^3＋ ions in crystals decrease along the growth direction, the absorption intensity and the fluorescence intensity ions also decrease along the growth direction. of Er^3＋ However, for the upper part crystal, the upconversion fluorescence intensity is higher than that of the lower part crystal excited with 800 or 970 nm pump. The effects of crystal lattice, structure defect and effective segregation of Er^3＋ ions were discussed in respect to the variations were discussed of upconversion fluorescence intensity.展开更多
A series of Yb：Tm：LiNbO_3 crystals doped with x mol% Hf^（4＋）ions（x = 2, 4, and 6） were grown by the Czochralski method. The dopant occupancy and defect structure of Hf：Yb：Tm：LiNbO_3 crystals were investigate...A series of Yb：Tm：LiNbO_3 crystals doped with x mol% Hf^（4＋）ions（x = 2, 4, and 6） were grown by the Czochralski method. The dopant occupancy and defect structure of Hf：Yb：Tm：LiNbO_3 crystals were investigated by x-ray diffraction and infrared transmission spectra. The influence of Hf^（4＋）ions concentration on UV–VIS–NIR absorption spectra of Hf：Yb：Tm：LiNbO_3 crystals was discussed. The upconversion luminescence of Hf：Yb：Tm：LiNbO_3 crystals was obtained under 980 nm excitation. Strong emissions were observed at 475 nm in the blue wavelength range and 651 nm in the red wavelength range. Remarkably, enhancement of the red and blue upconversion luminescence was achieved by tridoping Hf^（4＋）ions.展开更多
Fe（0.2 mol%）：Cu（0.04 mol%）：LiNbO3 crystals with different doping concentration of In^3＋ （0, 1.0, 2.0, 3.0mol%） were grown by Czochralski method, and then oxidized and reduced. The infrared transmittance spect...Fe（0.2 mol%）：Cu（0.04 mol%）：LiNbO3 crystals with different doping concentration of In^3＋ （0, 1.0, 2.0, 3.0mol%） were grown by Czochralski method, and then oxidized and reduced. The infrared transmittance spectra of crystals were measured to investigate the location of doping ion and its threshold concentration. The photorefractive properties of the crystals were tested by two beam coupling experiment. The results showed that the threshold concentration of In ions is 2.0～ 3.0 mol% and In ions take the place of NbLi^4＋ to form （ InLi^2＋） before reaching its threshold concentration, and then the location of normal Nb ions. In the （2.0 mol%）：Fe：Cu：LiNbO3 crystal with the oxidation treatment having the highest diffraction efficiency （η = 45.8%）, the photo-damage resistance threshold value R of In（3.0 mol%）：Fe：Cu：LiNbO3 was 3.67×10^4 W/cm^2 which was two orders of magnitude higher than that of Fe：Cu：LiNbO3 crystal （4.30×10^2 W/cm^2）. And the photo-damage resistance ability was enhanced by oxidized treatment. The In（2.0～3.0 mol%）：Fe：Cu：LiNbO3 crystals with oxidized treatment have the best photorefractive properties.展开更多
A series of Mg：In：Fe：LiNbO3 crystals were grown by Czochralski technique; their absorption spectra and photo scattering resistance ability after oxidation or reduction treatment were measured by light spot distorti...A series of Mg：In：Fe：LiNbO3 crystals were grown by Czochralski technique; their absorption spectra and photo scattering resistance ability after oxidation or reduction treatment were measured by light spot distortion method, and their response time and exponential gain coefficient were tested by two-beam coupling experiment. Besides, the effective carrier concentration has been calculated. The results showed that the absorption edges of reduced and oxidized crystals are respectively shifted to violet and Einstein compared with those of the growth state crystal. From oxidation state to growth state to reduction state of the samples, the photo scattering resistance ability and response time decrease while the exponential gain coefficient and concentration of effective carriers increase. The reduction treatment was necessary for the Mg：In：Fe：LiNbO3 crystals to enhance their photorefractive properties.展开更多
In：Fe：Mn：LiNbO3（LN） crystals were grown in air atmosphere by Czochralski method with different concentration of In （0, 1, 2, 3 mol%） in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, resp...In：Fe：Mn：LiNbO3（LN） crystals were grown in air atmosphere by Czochralski method with different concentration of In （0, 1, 2, 3 mol%） in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, respectively. The location of doping ions was analyzed by Ultravioletvisible absorption spectra and differential thermal analysis. The diffraction efficiency （η）, writing time （τw） and erasure time （τe） of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt, the absorption edge of In：Fe：Mn：LN crystal shifts to the violet firstly and then makes the Einstein shift, the Curie temperature of crystal increases firstly and then decreases, the storage ratio speeds up, diffraction efficiency decreases, and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In：Fe： Mn：LN crystal with different doping concentration of In^3＋ was investigated, suggesting the In： Fe：Mn：LN crystals are excellent holographic storage materiel with better synthetical properties than Fe：Mn：LN crystals.展开更多
The congruent tri-doped Mg:Mn:Fe:LiNbO 3 crystal has been grown by Czochralski method. Some crystal samples are reduced in Li 2CO 3 powder at 500 ℃ for 24 hours or oxidized for 10 hours at 1100 ℃ in Nb 2O 5 powder. ...The congruent tri-doped Mg:Mn:Fe:LiNbO 3 crystal has been grown by Czochralski method. Some crystal samples are reduced in Li 2CO 3 powder at 500 ℃ for 24 hours or oxidized for 10 hours at 1100 ℃ in Nb 2O 5 powder. Compared with As-grown Mg:Mn:Fe:LiNbO 3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample and the reduced shifts to the violet and the red, respectively. Reduction increases the absorption of crystals in visible light region. In two-wave coupling experiments, the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions are determined. The results indicate that oxidation and reduction disposing has great effect on the holographic recording properties of these crystals. The reduced crystal exhibits the fastest response time of 160 s among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO 3 crystals are investigated.展开更多
Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal s...Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal shape and hybrid shape of holes are theoretically analyzed. Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate （LiNbO3 ）, a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode, and useful transmission spectra with strong contrast and sharp band edges are achieved.展开更多
A series of Yb：Nd：LiNbO3 crystals tridoped with various concentrations of Zr4＋（1 mol.%, 2 mol.% and 4 mol.%） were grown by the Czochralski technique from the congruent melt. The X-ray powder diffraction, UV-Vis-N...A series of Yb：Nd：LiNbO3 crystals tridoped with various concentrations of Zr4＋（1 mol.%, 2 mol.% and 4 mol.%） were grown by the Czochralski technique from the congruent melt. The X-ray powder diffraction, UV-Vis-NIR absorption spectra and IR transmittance spectra were measured to analyze the crystal composition and defect structure. The Zr4＋, Yb3＋ and Nd3＋ ions in LiNbO3 crystal had two effects： volume compensation effect and ion valence state compensation effect. The Zr O2 doping threshold concentration was nearly 2.0 mol.%. The fluorescence emissions of Nd3＋ ions and Yb3＋ ions were observed under 808 nm excitation. The intensity of fluorescence emissions enhanced with the increasing of the Zr4＋ doping concentrations. The Zr：Yb：Nd：LiNbO3 crystals with 4 mol.% doping concentration of Zr4＋ ion revealed strong emission around 1 μm, which is of great significance for laser materials.展开更多
In this paper, photorefractive crystals of Ce, Fe:LiNbO 3 are systematically studied. The crystals have been grown by Czochralski method. The samples with different doping concentrations and oxidation/reduction treat...In this paper, photorefractive crystals of Ce, Fe:LiNbO 3 are systematically studied. The crystals have been grown by Czochralski method. The samples with different doping concentrations and oxidation/reduction treatments have been fabricated. Their photorefractive properties were experimentally investigated by using two beam coupling. The results show that the photorefractive efficiency depends on the dopant concentration, oxidation/reduction treatment, and light wavelength. The doping mechanism is also discussed here.展开更多
The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength ...The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.展开更多
This paper investigates the photovoltaic properties of miscut LiNbO3 single crystal with different thicknesses under irradiation of a 248 nm ultraviolet laser pulse with 20 ns duration without an applied bias. Nanosec...This paper investigates the photovoltaic properties of miscut LiNbO3 single crystal with different thicknesses under irradiation of a 248 nm ultraviolet laser pulse with 20 ns duration without an applied bias. Nanosecond photovoltaic response is observed and faster rise time is obtained in thinner samples. In accord with the 248 nm laser duration, the full width at half maximum of the photovoltaic signals keeps a constant of ~ 20 ns. With decrease of the crystal thickness, the photovoltaic sensitivity was improved rapidly at first and then decreased, and the maximum photovoltage occurred at 0.38 mm-thick single crystal. The present results demonstrate that decreasing the LiNbO3 single crystal thickness can obtain faster response time and improve the photovoltaic sensitivity.展开更多
Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the r...Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.展开更多
基金Project supported by Scientific Research Fund of Zhejiang Provincial Education Department (20061660)Foundation ofNingbo University (xk200435)
文摘The growth of LiNbO3 single crystal with Er^3＋ and Zn^2＋ co-doped using Bridgman method and its characteristic absorption spectra and fluorescence spectra were reported. Large-size crystals initially containing Zn^2＋ （3%） and Er^3＋ （0.6%） with good optical quality were obtained using optimized conditions such as a growth rate of 0.8- 1.5 mm·h^-1 and a temperature gradient of about 30 - 35℃·cm^-1 across the solid-liquid interface and the sealed platinum crucible. X-ray diffraction and differential thermal analysis （DTA） were used to characterize the crystals. The results indicate that the concentration of Er^3＋ ions in crystals, their absorption intensity, and their fluorescence intensity decrease from the bottom to the top in the crystals. However, for the upper part of the crystal, the up-conversion fluorescence intensity is higher than that of the lower part excited by an 800 or 970 nm pump. The effects of the crystal lattice, their structural defect and their effective segregation of Er^3＋ ions were discussed with respect to the variations of the up-conversion fluorescence intensity.
基金supported by the Fundamental Research Foundation of Commission of Science Technology,Industry for National Defense of China (Grant No.2320060089)and National Basic Research and Development Program of China (Grant No.2007CB3070001)Program of Excellent Team in Harbin Institute of Technology,China
文摘Photorefractive properties of Hf：Fe：LiNbO3 crystals with various [Li]/[Nb] ratios have been investigated at 488 nm wavelength based on the two-wave coupling experiment. High diffraction efficiency and large recording sensitivity are observed and explained. The decrease in Li vacancies is suggested to be the main contributor to the increase in the photoconductivity and subsequently to the induction of the improvement of recording sensitivity. The saturation diffraction efficiency is measured up to 80.2%, and simultaneously the recording sensitivity of 0.91 cm/J is achieved to in the Hf：Fe：LiNbO3 crystal grown from the melt with the [Li]/[Nb] ratio of 1.20, which is significantly enhanced as compared with those of the Hf：Fe：LiNbO3 crystal with the [Li]/[Nb] ratio of 0.94 in melt under the same experimental conditions. Experimental results definitely show that increasing the [Li]/[Nb] ratio in crystal is an effective method＇for Hf：Fe：LiNbO3 crystal to improve its photorefractive properties.
文摘The growth of LiNbO3 single crystal with Er^3＋/Zn^2＋ co-doped by the bridgman method and the characteristics of absorption spectra and fluorescence spectra were reported. By means of the optimized con- ditions such as growth rate of 0.8 - 1.5 mm · h^- 1, temperature gradient about 30 - 35℃ ·cm^-1 across the solid-liquid interface and sealed platinum, large size crystals containing Zn^2＋ （3%） and Er^3＋ （0.6%） with good optical quality were obtained. X-ray diffraction and DTA were used to characterize the crystals. The results indicate that the concentration of Er^3＋ ions in crystals decrease along the growth direction, the absorption intensity and the fluorescence intensity ions also decrease along the growth direction. of Er^3＋ However, for the upper part crystal, the upconversion fluorescence intensity is higher than that of the lower part crystal excited with 800 or 970 nm pump. The effects of crystal lattice, structure defect and effective segregation of Er^3＋ ions were discussed in respect to the variations were discussed of upconversion fluorescence intensity.
基金Project supported by Special Funds of Harbin Innovation Talents in Science and Technology Research,China(Grant No.2015RQQXJ045)Science Funds for the Young Innovative Talents of HUST,China
文摘A series of Yb：Tm：LiNbO_3 crystals doped with x mol% Hf^（4＋）ions（x = 2, 4, and 6） were grown by the Czochralski method. The dopant occupancy and defect structure of Hf：Yb：Tm：LiNbO_3 crystals were investigated by x-ray diffraction and infrared transmission spectra. The influence of Hf^（4＋）ions concentration on UV–VIS–NIR absorption spectra of Hf：Yb：Tm：LiNbO_3 crystals was discussed. The upconversion luminescence of Hf：Yb：Tm：LiNbO_3 crystals was obtained under 980 nm excitation. Strong emissions were observed at 475 nm in the blue wavelength range and 651 nm in the red wavelength range. Remarkably, enhancement of the red and blue upconversion luminescence was achieved by tridoping Hf^（4＋）ions.
基金This work was supported by Harbin Science and Technology Project (No. 2005AA5CG058)Natural Science Foundation of Heilongjiang Province (No. A0203)
文摘Fe（0.2 mol%）：Cu（0.04 mol%）：LiNbO3 crystals with different doping concentration of In^3＋ （0, 1.0, 2.0, 3.0mol%） were grown by Czochralski method, and then oxidized and reduced. The infrared transmittance spectra of crystals were measured to investigate the location of doping ion and its threshold concentration. The photorefractive properties of the crystals were tested by two beam coupling experiment. The results showed that the threshold concentration of In ions is 2.0～ 3.0 mol% and In ions take the place of NbLi^4＋ to form （ InLi^2＋） before reaching its threshold concentration, and then the location of normal Nb ions. In the （2.0 mol%）：Fe：Cu：LiNbO3 crystal with the oxidation treatment having the highest diffraction efficiency （η = 45.8%）, the photo-damage resistance threshold value R of In（3.0 mol%）：Fe：Cu：LiNbO3 was 3.67×10^4 W/cm^2 which was two orders of magnitude higher than that of Fe：Cu：LiNbO3 crystal （4.30×10^2 W/cm^2）. And the photo-damage resistance ability was enhanced by oxidized treatment. The In（2.0～3.0 mol%）：Fe：Cu：LiNbO3 crystals with oxidized treatment have the best photorefractive properties.
基金This work was supported by the Harbin Science and Technic Project (No. 2005AA5CG058)
文摘A series of Mg：In：Fe：LiNbO3 crystals were grown by Czochralski technique; their absorption spectra and photo scattering resistance ability after oxidation or reduction treatment were measured by light spot distortion method, and their response time and exponential gain coefficient were tested by two-beam coupling experiment. Besides, the effective carrier concentration has been calculated. The results showed that the absorption edges of reduced and oxidized crystals are respectively shifted to violet and Einstein compared with those of the growth state crystal. From oxidation state to growth state to reduction state of the samples, the photo scattering resistance ability and response time decrease while the exponential gain coefficient and concentration of effective carriers increase. The reduction treatment was necessary for the Mg：In：Fe：LiNbO3 crystals to enhance their photorefractive properties.
基金Harbin Science and Technology Project (No. 2005AA5CG058)Natural Science Foundation of Heilongjiang Province (No. A0203)
文摘In：Fe：Mn：LiNbO3（LN） crystals were grown in air atmosphere by Czochralski method with different concentration of In （0, 1, 2, 3 mol%） in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, respectively. The location of doping ions was analyzed by Ultravioletvisible absorption spectra and differential thermal analysis. The diffraction efficiency （η）, writing time （τw） and erasure time （τe） of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt, the absorption edge of In：Fe：Mn：LN crystal shifts to the violet firstly and then makes the Einstein shift, the Curie temperature of crystal increases firstly and then decreases, the storage ratio speeds up, diffraction efficiency decreases, and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In：Fe： Mn：LN crystal with different doping concentration of In^3＋ was investigated, suggesting the In： Fe：Mn：LN crystals are excellent holographic storage materiel with better synthetical properties than Fe：Mn：LN crystals.
基金The subject has been supported by Chinese National Advanced Technology 863 Project(Grant No.8632001AA31304)Chinese National 973 Project(Grant No.G19990330).
文摘The congruent tri-doped Mg:Mn:Fe:LiNbO 3 crystal has been grown by Czochralski method. Some crystal samples are reduced in Li 2CO 3 powder at 500 ℃ for 24 hours or oxidized for 10 hours at 1100 ℃ in Nb 2O 5 powder. Compared with As-grown Mg:Mn:Fe:LiNbO 3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample and the reduced shifts to the violet and the red, respectively. Reduction increases the absorption of crystals in visible light region. In two-wave coupling experiments, the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions are determined. The results indicate that oxidation and reduction disposing has great effect on the holographic recording properties of these crystals. The reduced crystal exhibits the fastest response time of 160 s among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO 3 crystals are investigated.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50872089,61077039 and 61377060the Research Grants Council of the Hong Kong Special Administrative Region of China under Grant No 11211014+1 种基金the Key Program for Research on Fundamental to Application and Leading Technology of Tianjin Science and Technology Commission of China under Grant No 11JCZDJC15500the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20100032110052
文摘Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed proton- exchange waveguide are numerically simulated. The effects of the finite depth, conical shape, trapezoidal shape and hybrid shape of holes are theoretically analyzed. Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate （LiNbO3 ）, a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode, and useful transmission spectra with strong contrast and sharp band edges are achieved.
基金supported by the Youth Science Fund of Heilongjiang Province of China(QC2015061)
文摘A series of Yb：Nd：LiNbO3 crystals tridoped with various concentrations of Zr4＋（1 mol.%, 2 mol.% and 4 mol.%） were grown by the Czochralski technique from the congruent melt. The X-ray powder diffraction, UV-Vis-NIR absorption spectra and IR transmittance spectra were measured to analyze the crystal composition and defect structure. The Zr4＋, Yb3＋ and Nd3＋ ions in LiNbO3 crystal had two effects： volume compensation effect and ion valence state compensation effect. The Zr O2 doping threshold concentration was nearly 2.0 mol.%. The fluorescence emissions of Nd3＋ ions and Yb3＋ ions were observed under 808 nm excitation. The intensity of fluorescence emissions enhanced with the increasing of the Zr4＋ doping concentrations. The Zr：Yb：Nd：LiNbO3 crystals with 4 mol.% doping concentration of Zr4＋ ion revealed strong emission around 1 μm, which is of great significance for laser materials.
文摘In this paper, photorefractive crystals of Ce, Fe:LiNbO 3 are systematically studied. The crystals have been grown by Czochralski method. The samples with different doping concentrations and oxidation/reduction treatments have been fabricated. Their photorefractive properties were experimentally investigated by using two beam coupling. The results show that the photorefractive efficiency depends on the dopant concentration, oxidation/reduction treatment, and light wavelength. The doping mechanism is also discussed here.
基金Supported by the National Natural Science Foundation of China (Grant No. 10475052) and the Scientific Research Start-up Financing of Qufu Normal University
文摘The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.
基金supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-08-0841)the National Natural Science Foundation of China (Grant Nos. 60778034 and 60877038)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 200804250006)Beijng Natural ScienceFoundation (Grant No. 4082026)
文摘This paper investigates the photovoltaic properties of miscut LiNbO3 single crystal with different thicknesses under irradiation of a 248 nm ultraviolet laser pulse with 20 ns duration without an applied bias. Nanosecond photovoltaic response is observed and faster rise time is obtained in thinner samples. In accord with the 248 nm laser duration, the full width at half maximum of the photovoltaic signals keeps a constant of ~ 20 ns. With decrease of the crystal thickness, the photovoltaic sensitivity was improved rapidly at first and then decreased, and the maximum photovoltage occurred at 0.38 mm-thick single crystal. The present results demonstrate that decreasing the LiNbO3 single crystal thickness can obtain faster response time and improve the photovoltaic sensitivity.
基金the financially support of the National Natural Science Foundation of China(12164051)the Joint Foundation of Provincial Science and Technology Department-Double First-class Construction of Yunnan University(2019FY003016)+4 种基金the Young Top Talent Project of Yunnan Province(YNWR-QNBJ-2018-229)the financially support by Yunnan Major Scientific and Technological Projects(202202AG050016)Advanced Analysis and Measurement Center of Yunnan University for the sample characterization service and the Postgraduate Research and Innovation Foundation of Yunnan University(2021Y036)the financially support of the National Natural Science Foundation of China(62064013)the Application Basic Research Project of Yunnan Province[2019FB130]。
文摘Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.
