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
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
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
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
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
In 2O 3, MgO and Fe 2O 3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO 3 crystals. The OH - extension transmission spectra, light scattering resistance ability, two wave coupled dif...In 2O 3, MgO and Fe 2O 3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO 3 crystals. The OH - extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO 3 crystal. We discussed the site of In, Mg and Fe in LiNbO 3 crystals and the influence of the absorption peak of OH - transmission spectra on photorefractive property for LiNbO 3 crystal.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
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
LiNbO 3crystal possesses electro optic effect and nonlinear optical effect.Bec ars e it is easy to generate photo damage(photorefractive) for LiNbO 3.This limits i ts application in some fields.When doping 6mol% ZnO o...LiNbO 3crystal possesses electro optic effect and nonlinear optical effect.Bec ars e it is easy to generate photo damage(photorefractive) for LiNbO 3.This limits i ts application in some fields.When doping 6mol% ZnO or 5mol% MgO in LiNbO 3 cry stal to grow Zn∶LiNbO 3 or Mg∶LiNbO 3 crystal,the photo damage resistance ab ility fo these two crystals is two orders of magnitude higher than that of LiNbO 3.We doped 3mol% ZnO and 3mol% MgO to grow Zn∶Mg∶LiNbO 3 crystal and used Fourier spectrophotometer to measure the infrared transmission spectra.The waven umber range to measure the OH - stretched vibration transmission spectra of Zn ∶LiNbO 3,Mg∶LiNbO 3 and Zn∶Mg∶LiNbO 3 crystal is 3200 4000cm -1 .The measurement result is that the OH - stretched vibration absorption peak of Zn( 6mol%):LiNbO 3,Mg(5mol%):LiNbO 3 and Zn(3mol%):Mg(3mol%):LiNbO 3 crystal is at 3535cm -1 (2.83μm),while that of pure LiNbO 3,Zn(3mol%):LiNbO 3 and M g(3mol%):LiNbO 3 is at 3484cm -1 (2.87μm).We take the direct obseration me thod of the focula distortion in crystal to measure the photorefractive threshol d value of these crystals and gained the result that the photorefractive thresho ld value of Zn(6mol%):LiNbO 3,Mg(5mol%):LiNbO 3 and Zn(3mol%):Mg(3mol%):LiNbO 3 increase above two orders of magnitude higher than pure LiNbO 3 crystal and the photorefractive threshold value of Zn(3mol%):LiNbO 3 and Mg(3mol%):LiNbO 3 is a little higher than that of pure LiNbO 3 crystal.The congruent compositio n ratio of LiNbO 3 is Li/Nb=0.946.A part of Nb 5+ take place Li + site to form the intrinsic defect antisite Nb 4+ Li .The charge transport proc ess in LiNbO 3 is due to this kind of intrinsic defect.Especially in high light intensity,the intrinsic defect is important.The quantity that make antisite Nb 4+ Li defect structure disappear when doping ions (Mg 2+ and Zn 2+ ) substitute for all Nb 4+ Li at Li + site is called the thre shold concentration for this impurity ion.At the same time the impurity ion star t to take place Nb site.The photo damage resistance impurity ion is to drive ant i site Nb Li from Li site to normal Nb site so that the OH - absorption peak shifts to 2.83μm from 2.87μm.The fact that the OH - absorption peak of Zn(3m ol%):Mg(3mol%):LiNbO 3 crystal shifts to 2.83μm from 2.87μm and its photo dam age resistance threshold value is two orders of magnitude higher than pure LiNbO 3 crystal shows that above analyse is reasonable.展开更多
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 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.
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
文摘In 2O 3, MgO and Fe 2O 3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO 3 crystals. The OH - extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO 3 crystal. We discussed the site of In, Mg and Fe in LiNbO 3 crystals and the influence of the absorption peak of OH - transmission spectra on photorefractive property for LiNbO 3 crystal.
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.
文摘LiNbO 3crystal possesses electro optic effect and nonlinear optical effect.Bec ars e it is easy to generate photo damage(photorefractive) for LiNbO 3.This limits i ts application in some fields.When doping 6mol% ZnO or 5mol% MgO in LiNbO 3 cry stal to grow Zn∶LiNbO 3 or Mg∶LiNbO 3 crystal,the photo damage resistance ab ility fo these two crystals is two orders of magnitude higher than that of LiNbO 3.We doped 3mol% ZnO and 3mol% MgO to grow Zn∶Mg∶LiNbO 3 crystal and used Fourier spectrophotometer to measure the infrared transmission spectra.The waven umber range to measure the OH - stretched vibration transmission spectra of Zn ∶LiNbO 3,Mg∶LiNbO 3 and Zn∶Mg∶LiNbO 3 crystal is 3200 4000cm -1 .The measurement result is that the OH - stretched vibration absorption peak of Zn( 6mol%):LiNbO 3,Mg(5mol%):LiNbO 3 and Zn(3mol%):Mg(3mol%):LiNbO 3 crystal is at 3535cm -1 (2.83μm),while that of pure LiNbO 3,Zn(3mol%):LiNbO 3 and M g(3mol%):LiNbO 3 is at 3484cm -1 (2.87μm).We take the direct obseration me thod of the focula distortion in crystal to measure the photorefractive threshol d value of these crystals and gained the result that the photorefractive thresho ld value of Zn(6mol%):LiNbO 3,Mg(5mol%):LiNbO 3 and Zn(3mol%):Mg(3mol%):LiNbO 3 increase above two orders of magnitude higher than pure LiNbO 3 crystal and the photorefractive threshold value of Zn(3mol%):LiNbO 3 and Mg(3mol%):LiNbO 3 is a little higher than that of pure LiNbO 3 crystal.The congruent compositio n ratio of LiNbO 3 is Li/Nb=0.946.A part of Nb 5+ take place Li + site to form the intrinsic defect antisite Nb 4+ Li .The charge transport proc ess in LiNbO 3 is due to this kind of intrinsic defect.Especially in high light intensity,the intrinsic defect is important.The quantity that make antisite Nb 4+ Li defect structure disappear when doping ions (Mg 2+ and Zn 2+ ) substitute for all Nb 4+ Li at Li + site is called the thre shold concentration for this impurity ion.At the same time the impurity ion star t to take place Nb site.The photo damage resistance impurity ion is to drive ant i site Nb Li from Li site to normal Nb site so that the OH - absorption peak shifts to 2.83μm from 2.87μm.The fact that the OH - absorption peak of Zn(3m ol%):Mg(3mol%):LiNbO 3 crystal shifts to 2.83μm from 2.87μm and its photo dam age resistance threshold value is two orders of magnitude higher than pure LiNbO 3 crystal shows that above analyse is reasonable.
