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
Mg：Ru：Fe：LiN-bO3 crystals with various concentrations of MgO （in mole） and fixed content of RuO2 and Fe203 （in mass） are grown with the Czochralski method from the congruent melt. Their infrared transmission sp...Mg：Ru：Fe：LiN-bO3 crystals with various concentrations of MgO （in mole） and fixed content of RuO2 and Fe203 （in mass） are grown with the Czochralski method from the congruent melt. Their infrared transmission spectra are mea- sured and discussed to investigate the defect structure. With the increase of Mg2＋ concentration the blue nonvolatile holographic storage capability is enhanced. The nonvolatile holographic storage properties of dual-wavelength recording of Mg（7 mol%）：Ru：Fe：LiNbO3 nonvolatile diffraction efficiency, response time, and nonvolatile sensitivity reach 59.8%, 70 s, and 1.04 cm/J, respectively. Comparing Mg（7 mol%）：Ru：Fe：LiNbO3 with Ru：Fe：LiNbO3 crystal, the response time is shortened apparently. The nonvolatile diffraction efficiency and sensitivity are raised largely. The mechanism in blue photorefractive nonvolatile holographic storage is discussed.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
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 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
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
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
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
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
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.
基金Project supported by the Fundamental Research Funds for the Central Universities of China (Grant No. DL12AB03)the National Natural Science Founda-tion of China (Grant No. 60777006)
文摘Mg：Ru：Fe：LiN-bO3 crystals with various concentrations of MgO （in mole） and fixed content of RuO2 and Fe203 （in mass） are grown with the Czochralski method from the congruent melt. Their infrared transmission spectra are mea- sured and discussed to investigate the defect structure. With the increase of Mg2＋ concentration the blue nonvolatile holographic storage capability is enhanced. The nonvolatile holographic storage properties of dual-wavelength recording of Mg（7 mol%）：Ru：Fe：LiNbO3 nonvolatile diffraction efficiency, response time, and nonvolatile sensitivity reach 59.8%, 70 s, and 1.04 cm/J, respectively. Comparing Mg（7 mol%）：Ru：Fe：LiNbO3 with Ru：Fe：LiNbO3 crystal, the response time is shortened apparently. The nonvolatile diffraction efficiency and sensitivity are raised largely. The mechanism in blue photorefractive nonvolatile holographic storage is discussed.
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.
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.
文摘在 Fe∶Li Nb O3 中掺进 3 mol%和 6mol% Mg O,生长了 Mg∶Fe∶L i Nb O3 晶体 .测试了 Mg∶Fe∶Li Nb O3 晶体抗光致散射能力、衍射效率、响应时间和光电导 .推导响应时间与光电导之间的关系 .在 Fe∶Li Nb O3 晶体中掺进 6mol%的 Mg2 + ,它的抗光致散射能力比Fe∶L i Nb O3 晶体提高一个数量级 ,响应速度比 Fe∶Li Nb O3
