We have grown triply doped Mg:Fe:Mn:LiTaO3 crystals with near stoichiometry using the top seeded solution growth technique. The defect structure was investigated by infrared absorption spectra and Curie temperature. U...We have grown triply doped Mg:Fe:Mn:LiTaO3 crystals with near stoichiometry using the top seeded solution growth technique. The defect structure was investigated by infrared absorption spectra and Curie temperature. Using a blue laser as the source, excellent photorefractive properties were obtained. Nonvolatile holographic storage properties were investigated using the dual wavelength technique. We got a very high fixed diffraction efficiency and nonvolatile holographic storage sensitivity. The blue light has more than enough energy to excite holes of deep(Mn) and shallow(Fe) trap centers with the same phase, which enhance dramatically the blue photorefractive properties and the nonvolatile holographic storage. Mg2+ ion is no longer damage resistant at blue laser, but enhances photorefractive characteristics.展开更多
This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium...This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium niobate crystal Besides Fe^2＋ and Fe^3＋ ions, small polarons and bipolarons are considered as another photoactive centre.展开更多
A new method to suppress the fanning noise caused by He-Ne laser in the cooperation with Ar+laser in photorefractive LiNbO_(3):Fe crystal was successfully realized.This method is simple and efficient.By using this met...A new method to suppress the fanning noise caused by He-Ne laser in the cooperation with Ar+laser in photorefractive LiNbO_(3):Fe crystal was successfully realized.This method is simple and efficient.By using this method,fanning-noise-free hologram can be stored in LiNbO_(3):Fecrystal.展开更多
The mechanism for the high-performance KNSBN:Cu crystal self-pumped phase-conjugator is first put forward in this letter as no-loop photorefractive self-bending succesive four-wave mixing interaction.And the photore f...The mechanism for the high-performance KNSBN:Cu crystal self-pumped phase-conjugator is first put forward in this letter as no-loop photorefractive self-bending succesive four-wave mixing interaction.And the photore fractive backscattering amplification was found to play a very important role in it.展开更多
KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, expo...KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, exponential gain coefficient （Г） and thin crystal sheet effect, were measured. The results showed that the two spectra resembling Ce：Nd：KLN crystal were of tetragonal tungsten bronze structure, the exponential gain coefficient of Ce：Nd：KLN crystal was higher than that of KLN crystals and Ce：Nd：KLN crystal had thin crystal sheet effect, for its exponential gain coefficient increasing with crystal sheet thinning. The thin crystal sheet effect of Ce：Nd：KLN crystal was also discussed.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 this paper, photorefractive crystals of Cu-doped (K0.5Na0.5)0.2 (Sr0.75Ba0.25)0.9Nb2O6 (KNSBN) are systematically studied. A series of Cu-doped KNSBN crystals have been grown and the samples with Cu-dopant in diffe...In this paper, photorefractive crystals of Cu-doped (K0.5Na0.5)0.2 (Sr0.75Ba0.25)0.9Nb2O6 (KNSBN) are systematically studied. A series of Cu-doped KNSBN crystals have been grown and the samples with Cu-dopant in different levels and thicknesses have been fabricated. Their photorefractive properties including two-wave coupling gain coefficients and response rate are experimentally studied in details. The results show that (1) with high Cudopant cocentration, the crystal has larger coupling gain coefficient, higher effective charge carrier density, and faster time response; (2) thinner sample shows larger coupling gain coefficientl (3) at shorter wavelength 9 the crystal sample shows larger coupling gain coefficient and faster time response. The Cu-doping mechanisms were briefly referred. The analyses of the relationships among the crystal’s two-wave coupling, absorption property and the self-pumped phase conjugation are given. All the results show that Cu-doped KNSBN crystals are a kind of very promising photorefractive 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
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
We observe obviously different diffraction efficiencies with forward and reverse dc voltages in a forced-light-scattering(FLS)experiment for a cell with ZnO nanorod doped in only one poly(vinyl alcohol)(PVA)layer.When...We observe obviously different diffraction efficiencies with forward and reverse dc voltages in a forced-light-scattering(FLS)experiment for a cell with ZnO nanorod doped in only one poly(vinyl alcohol)(PVA)layer.When a dc voltage with a positive pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the transverse direction,which results in a higher diffraction efficiency.Conversely,when the dc voltage with a negative pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the longitudinal direction,which leads to a lower diffraction efficiency.A largest diffraction efficiency of about 9%is achieved in the ZnO nanorod doped liquid crystal cell.展开更多
A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for st...A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for steady-state photorefractive slant grating recording has been obtained.It is shown that the inclusion of the longitudinal component of the space-charge field during photorefractive two-wave coupling can predict reduction of the fundamental harmonic and enhancement or reduction of the second-order harmonic for various applied field strength and various grating slant angles.The dependence of the first two-order harmonics on the slant angle and on the applied field strength is examined.展开更多
In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct...In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.展开更多
A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asym...A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like（PR-like） effect.展开更多
Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we pr...Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations： dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.展开更多
Lithitum niobate （LiNbO<sub>3</sub>, LN） crystal is an important type of photorefractive materi-als, its photorefractive property can be improved effectively by doping. For example, theoptical damage res...Lithitum niobate （LiNbO<sub>3</sub>, LN） crystal is an important type of photorefractive materi-als, its photorefractive property can be improved effectively by doping. For example, theoptical damage resistanee and the photorefractive sensitivity of LN crystal can be inerasedby doping Mg and Fe, respectively. Modest treatment of oxidation and reduction展开更多
Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an i...Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an interferogram of two plane waves.展开更多
With the progress of research on the applications of photorefractive (PR)effect in recent years, people paid more and more attention to the PR materials, especially to the modification of their properties, in order to...With the progress of research on the applications of photorefractive (PR)effect in recent years, people paid more and more attention to the PR materials, especially to the modification of their properties, in order to get crystals or ceramics with high optical quality展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No. 51202045）, the Postdoctoral Science Foundation of Heilongjiang Province, China, and the Fundamental Research Funds for the Central Universities of Ministry of Education of China （Grant No. HIT. NSRIF. 2013004）.
文摘We have grown triply doped Mg:Fe:Mn:LiTaO3 crystals with near stoichiometry using the top seeded solution growth technique. The defect structure was investigated by infrared absorption spectra and Curie temperature. Using a blue laser as the source, excellent photorefractive properties were obtained. Nonvolatile holographic storage properties were investigated using the dual wavelength technique. We got a very high fixed diffraction efficiency and nonvolatile holographic storage sensitivity. The blue light has more than enough energy to excite holes of deep(Mn) and shallow(Fe) trap centers with the same phase, which enhance dramatically the blue photorefractive properties and the nonvolatile holographic storage. Mg2+ ion is no longer damage resistant at blue laser, but enhances photorefractive characteristics.
基金Project supported by the research funding via Program for Changjiang Scholars of ChinaInnovative Research Team in University,China+1 种基金the National Natural Science Foundation of China(Grant No60578019)Program for Changjiang Scholars and Innovative Research Team in University
文摘This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium niobate crystal Besides Fe^2＋ and Fe^3＋ ions, small polarons and bipolarons are considered as another photoactive centre.
基金Supported by the National Natural Science Foundation of China,and the National Climbing Programme of Fundamental Research。
文摘A new method to suppress the fanning noise caused by He-Ne laser in the cooperation with Ar+laser in photorefractive LiNbO_(3):Fe crystal was successfully realized.This method is simple and efficient.By using this method,fanning-noise-free hologram can be stored in LiNbO_(3):Fecrystal.
基金Supported by the National Natural Science Foundation of ChinaTianjin Science Foundation for Youth.
文摘The mechanism for the high-performance KNSBN:Cu crystal self-pumped phase-conjugator is first put forward in this letter as no-loop photorefractive self-bending succesive four-wave mixing interaction.And the photore fractive backscattering amplification was found to play a very important role in it.
文摘KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, exponential gain coefficient （Г） and thin crystal sheet effect, were measured. The results showed that the two spectra resembling Ce：Nd：KLN crystal were of tetragonal tungsten bronze structure, the exponential gain coefficient of Ce：Nd：KLN crystal was higher than that of KLN crystals and Ce：Nd：KLN crystal had thin crystal sheet effect, for its exponential gain coefficient increasing with crystal sheet thinning. The thin crystal sheet effect of Ce：Nd：KLN crystal was also discussed.
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.
文摘In this paper, photorefractive crystals of Cu-doped (K0.5Na0.5)0.2 (Sr0.75Ba0.25)0.9Nb2O6 (KNSBN) are systematically studied. A series of Cu-doped KNSBN crystals have been grown and the samples with Cu-dopant in different levels and thicknesses have been fabricated. Their photorefractive properties including two-wave coupling gain coefficients and response rate are experimentally studied in details. The results show that (1) with high Cudopant cocentration, the crystal has larger coupling gain coefficient, higher effective charge carrier density, and faster time response; (2) thinner sample shows larger coupling gain coefficientl (3) at shorter wavelength 9 the crystal sample shows larger coupling gain coefficient and faster time response. The Cu-doping mechanisms were briefly referred. The analyses of the relationships among the crystal’s two-wave coupling, absorption property and the self-pumped phase conjugation are given. All the results show that Cu-doped KNSBN crystals are a kind of very promising photorefractive 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by the National Natural Science Foundation of China(60625402,60990313)the 973 programme(2006CB604908,2006CB921607).
文摘We observe obviously different diffraction efficiencies with forward and reverse dc voltages in a forced-light-scattering(FLS)experiment for a cell with ZnO nanorod doped in only one poly(vinyl alcohol)(PVA)layer.When a dc voltage with a positive pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the transverse direction,which results in a higher diffraction efficiency.Conversely,when the dc voltage with a negative pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the longitudinal direction,which leads to a lower diffraction efficiency.A largest diffraction efficiency of about 9%is achieved in the ZnO nanorod doped liquid crystal cell.
基金Supported by the Natural Science Foundation of Heilongjiang Province。
文摘A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for steady-state photorefractive slant grating recording has been obtained.It is shown that the inclusion of the longitudinal component of the space-charge field during photorefractive two-wave coupling can predict reduction of the fundamental harmonic and enhancement or reduction of the second-order harmonic for various applied field strength and various grating slant angles.The dependence of the first two-order harmonics on the slant angle and on the applied field strength is examined.
基金supported by the National Natural Science Foundations of China(Grant Nos 10174025 and 10574051)
文摘In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.
基金Project supported by the Science and Technology Programs of the Educational Committee of Heilongjiang Province,China(Grant No.12541730)the National Natural Science Foundation of China(Grant No.61405057)
文摘A new scheme for recording a dynamic phase grating with an asymmetric profile in C60-doped homeotropically aligned nematic liquid crystal（NLC） was presented.An oblique incidence beam was used to record the thin asymmetric dynamic phase holographic grating.The diffraction efficiency we achieved is more than 40%,exceeding the theoretical limit for symmetric profile gratings.Both facts can be explained by assuming that a grating with an asymmetric saw-tooth profile is formed in the NLC.Finally,physical mechanism and mathematical model for characterizing the asymmetric phase holographic grating were presented,based on the photo-refractive-like（PR-like） effect.
文摘Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations： dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.
基金Project supported by the National Natural Science Foundation of China.
文摘Lithitum niobate （LiNbO<sub>3</sub>, LN） crystal is an important type of photorefractive materi-als, its photorefractive property can be improved effectively by doping. For example, theoptical damage resistanee and the photorefractive sensitivity of LN crystal can be inerasedby doping Mg and Fe, respectively. Modest treatment of oxidation and reduction
文摘Waveguides were fabricated in lithium niobate crystals solely by light irradiation using binary optical masks and SLM-prepared optical masks. Arrayed-waveguides were also obtained by once or twice irradiations of an interferogram of two plane waves.
文摘With the progress of research on the applications of photorefractive (PR)effect in recent years, people paid more and more attention to the PR materials, especially to the modification of their properties, in order to get crystals or ceramics with high optical quality
