The congruent Fe (0.03%wt):LiNbO3 crystals doped with different concentration of MgO (0, 2, 4, 6 mol%) were grown by Czochralski method in air atmosphere. The ultraviolet-visible absorption spectra, infrared absorption spectra of the crystals were measured in order to analyze their structure. The absorption edge of the Mg: Fe: LiNbO3 crystals shifted to the ultraviolet band compared with that of Fe: LiNbO3. The OH- absorption peaks of I and II crystals located at about 3483cm-1, while those of III and IV crystals shifted to 3536cm-1. The mechanism of OH- absorption peak shifting was studied. The light scattering ability resistance of Mg: Fe: LiNbO3 crystal was observed by straightly observing transmission facula distortion method. It indicated that light scattering ability resistance of III crystals was three orders of magnitude higher than that of Fe: LiNbO3 crystals. The exponential gain coefficient, diffraction efficiency and respond time of Mg: Fe: LiNbO3 crystals were measured by two-wave-coupling technology. The results indicate that exponential gain coefficient of Mg: Fe: LiNbO3 crystal was almost four times as that of iron-doped LiNbO3 and the response time exhibited four times shorter than that of iron-doped LiNbO3. Furthermore, the dynamic range was also calculated by the expression: M # = (τe ∠√η)/τω. The results indicated that Mg (4 mol%): Fe:LiNbO3 was the most proper holographic recording media material among four crystals in the paper.
The congruent Nd (Nd: 0. 2 wt %): LiNbO3 crystals doped with different concentration of MgO (MgO: 1, 3, 5,7mol %) have been grown by Czochralski method in air atmosphere. The crystals were made into samples after polarization, cut and polishing.
The infrared absorption spectra of Mg: Nd: LiNbO3 crystals were measured by using Fourier transform infrared spectrophotometer. The OH- absorption peaks of Mg (1mol %): Nd (0.2wt %): LiNbO3 crystal and Mg (3mol %): Nd (0.2wt %): LiNbO3 crystal located at about 3481cm-1, while that of Mg (5mol %): Nd (0.2wt %): LiNbO3 crystal and Mg (7mol %): Nd (0.2wt %): LiNbO3 crystal shifted to 3536cm-1. The mechanism of OH- absorption peak shifting was studied.
The resistance to photodamage of Mg: Nd: LiNbO3 crystals were measured by light spot distortion method. The results show that the photodamage threshold of Mg (5mol %) :Nd(0.2wt%):LiNbO3 was the highest(9.0×104W/cm2) among the samples. The mechanism of the photodamage resistance ability of Mg:Nd:LiNbO3 increasing was investigated.
Using a Q adjustable Nd: YAG laser as pumping light, the second harmonic generation (SHG) properties, including the phase matching temperature and SHG conversation efficiency of Mg: Nd: LiNbO3 were measured by 90 degree angle phase matching technology. The results showed that the SHG conversation efficiency of Mg (5mol %): Nd (0.2wt %): LiNbO3 was the highest (52%) among the samples at 96°C.
In:Er:LiNbO3 crystals with fixed Er concentration of 1mol% and variable In concentration of 1mol%, 2mol% and 3mol% have been grown by the Czochralski method, and then was made into waveguide substrates. The directly observing facula method was employed to measure the photo-damage resistance ability of the substrates, and it is found that In(3mol%):Er:LiNbO3 has the highest photo-damage resistance ability among these three substrates. The structure was determined by the infrared transmittance spectra and the UV absorption spectra. The mechanism that the photo-damage resistance ability of the substrates increases with the increase of the doped concentration of In was discussed via the structure of the crystal.
Zn ions were added into melts with 4.0mol.%, Fe ions were with 0.02mol.%, and In ions were with varying concentration of 0, 1.0, 2.0 and 3.0mol.%. A series of Zn:In:Fe:LiNbO3 Crystals were grown by Czochralski technique. Their absorption spectra and photo-damage resistant ability were measured. The mechanism of the shift of OH- absorption peak was investigated. Their photorefractive properties were experimentally investigated by using two-beam coupling. The results shown that, the photo-damage resistant ability of Zn(4mol.%):In(3mol.%): Fe(0.02mol.%):LiNbO3 Crystals were two orders than that of magnitude higher than that of Fe:LiNbO3 crystals, and with concentration of Zn and In ions increasing, diffraction efficiency and response time of crystals were shortened. The experiment of associative memory were also carried out with Zn(4mol.%):In(3mol.%):Fe(0.02mol.%):LiNbO3 crystals for the recording device and with Zn(4mol.%):In(2mol.%):Fe(0.02mol.%):LiNbO3 Crystals for phase conjugation.
The optical properties of the Ce:Cu:LiNbO3 co-doped with different concentrations of In were measured, including absorption spectra, infrared transmittance spectra and holographic storage properties. The doped threshold of In was determined via the results of spectrum measurement. When the doped concentration of In is over its threshold, the photo-damage resistance ability of In:Ce:Cu:LiNbO3 is improved dramatically. In the measurement of holographic storage properties, the response time of 34s, diffraction efficiency of 33%, and exponential gain coefficient of 18cm-1 were obtained for In(3mol%):Ce(0.20wt%):Cu(0.015wt%):LiNbO3 crystal.
The materials ratio is compounded followed by the molecular formula Ba0.5Sr1.5K0.5Na0.5Nb5O15. Doping 0.05 wt% CeO2 and 0.03 wt% Co2O3 in KNSBN, Ce:Co:KNSBN crystal was grown by Czochralski technique adopting SiMo heater furnace. The exponential gain coefficient, diffraction efficiency and response time of Ce:Co:KNSBN crystal were measured through two-beam couple light path. The phase conjugation reflect efficiency and response time of Ce:Co:KNSBN and Cu:SBN crystals were measured by four-wave mixing light path. The holographic associative storage were established by using Ce:Co:KNSBN crystal as recording apparatus and Cu:SBN crystal as phase conjugation lens. Addressing was operated by 75% and 50% images and the associative storage reappearing images are clear, complete and noise was small. The photo-refractive effects of Ce:Co:KNSBN crystal are more excellent than KNSBN crystal.
Congruent Eu:Fe:LiNbO3 crystals doped with or without fluxing agent K2O have been grown by TSSG method and the Czochralski method, respectively. The holographic storage properties, diffraction efficiency, response time and photoconduction, of the two Eu:Fe:LiNbO3 crystals are characterized by two-wave coupling experiment. Eu:Fe:LiNbO3 doped with fluxing agent K2O (Eu:Fe:SLN) has the higher photorefractive performances than congruent Eu:Fe:LiNbO3 (Eu:Fe:CLN). The nonvolatile holographic storage is realized in Eu:Fe:SLN crystals by using He-Ne laser as the light source and ultraviolet as the gating light.
Using Si-Mo Bar as the heater, potassium sodium barium strontium niobate (KNSBN) crystals doped with Ce and/or Eu have been grown by the Czochralski method. The exponential gain coefficients were measured by two-wave coupling light path, and in comparison with KNSBN, that of Ce:Eu:KNSBN is one time higher. Holographic associative storage principle is represented here and the holographic associative storage is realized by using Ce:Eu:KNSBN as the storage element and Mg:Fe:LiNbO3 as the phase conjugator to feedback, fetch threshold and gain. The output images are integrated.
Mg(3mol%):Mn:Fe:LiNbO3 and Mg(7mol%):Mn:Fe:LiNbO3 crystals have been grown by doping 3mol%, 7mol% MgO in Mn:Fe:LiNbO3, respectively. It was found that light scattering resistance ability of Mg(7mol%):Mn:Fe:LiNbO3 is two orders of magnitude higher than that of Mn:Fe:LiNbO3 crystals. In Mg:Mn:Fe:LiNbO3 crystal, Mn is deep level and Fe is shallow level. We selected Mg(3mol%):Mn:Fe:LiNbO3 as the storage medium to carry the two-photon holographic storage experiment by using He-Ne laser as recording light and ultraviolet (UV) light as sensitizing light. The single photon recording and erasure curves as well as those of double photon were measured also. The recording speed of Mg:Mn:Fe:LiNbO3 crystals is faster than that of Mn:Fe:LiNbO3.
Ce:Cu:BSO crystal co-doped with CeO2 and CuO has been grown by the Czochralski method. The lattice constants, absorption spectrum, exponential gain coefficient, diffraction efficiency and respond time are measured. The lattice constants of Ce:Cu:BSO crystal are always larger than that of BSO crystal. Due to Ce and Cu ionic radii are larger than that of Bi3+ and Si4+, the lattice constants of doped crystal are larger than that of BSO crystal, thus make the absorption edge shift to the longer wavelength spectral range. The results indicate that the photorefraction of Ce:Cu:BSO crystal improves and the exponential gain coefficient and diffraction efficiency of Ce:Cu:BSO crystal improves two times compared with that of undoped BSO crystal. Furthermore, the photorefractive effect and the holographic storage effect of Ce:Cu:BSO crystal is better than that of undoped BSO crystal.
Ce:Fe:LiNbO3 crystal co-doped with CeO2 and Fe2O3 is grown by Czochralski method with Si-C bars as heaters. The exponential gain coefficient, diffraction efficiency and respond time of Ce:Fe:LiNbO3 crystal are measured by two-wave-coupling technology. The results indicate that the exponential gain coefficient of Ce:Fe:LiNbO3 is up to 22cm-1 and the diffraction efficiency is 78% and the photorefractive effect is better than that of Fe:LiNbO3 crystal. A thermal fixing experiment is carried on the Ce:Fe:LiNbO3 crystal, which conditions are that the crystal is heated to 120°C, the activated energy and the developing efficiency of Ce:Fe:LiNbO3 crystal are measured, and the decay time of a fixed grating is up to 110 years at the room temperature (20°C).
Mg:Fe:LiTaO3 crystals were first grown by Czochralski method, and Fe:LiTaO3 crystals, Fe:LiNbO3 and Mg:Fe:LiNbO3 crystals were also grown at the same time. The holographic storage properties of these crystals, such as the exponential gain coefficient, the diffraction efficiency and the response time, were measured by the two-wave coupling method. It was found that the response speed of Mg:Fe:LiTaO3 crystal was five times faster than that of Fe:LiTaO3. The light scattering resistance ability was also measured, and that of Mg:Fe:LiTaO3 crystal was two orders of magnitude higher than that of Fe:LiTaO3 as well as higher than that of Mg:Fe:LiNbO3. The enhancement mechanism of the photorefractive properties for Mg:Fe:LiTaO3 crystal was discussed for the first time.
The absorption spectra and the optical damage resistance ability of the In:Fe:LiNbO3 crystals grown by Czochralski method with different concentration of In2O3 were measured. The absorption edges of the absorption spectra of the In:Fe:LiNbO3 crystals shift to the short wavenumbers with the concentration of the In2O3 in the crystal increasing. The optical damage resistance ability of the In(3.0mol%):Fe:LiNbO3 crystal is two orders magnitude higher than that of Fe:LiNbO3 crystal. The response speed of the In:Fe:LiNbO3 crystals increases with the concentration of the In2O3 in the crystal increasing, on the contrary, the diffraction efficiency decreases.
The congruent tri-doped Mg:Mn:Fe:LiNbO3 crystals have been grown by Czochralski method in air atmosphere. The crystal samples are reduced in Li2CO3 powder at 500°C for 24 hours or oxidized for 10 hours at 1100°C in Nb2O5 powder. Compared with as-grown Mg:Mn:Fe:LiNbO3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample or the reduced shifts to the red. The post-disposal, oxidation or reduction disposing has no effect on O-H vibration absorption peak in infrared region. In two coupling experiments we determine the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions. 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 145s and the biggest diffraction efficiency 67% among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO3 crystals has been investigated.
CuO and Co2O3 were doped in KNSBN and Czochralski method was used to grow Cu:Co:KNSBN crystal for the first time. ZnO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow Zn:Fe:LiNbO3 crystals. The diffraction efficiency and response time of the Zn:Fe:LiNbO3 crystals were measured. The response speed of the Zn:Fe:LiNbO3 crystal is four times higher than that of the Fe:LiNbO3 crystal. The self-pumping phase conjugate reflectivity and respond time of the Cu:Co:KNSBN crystal were measured. The result shows that the self-pumping phase conjugate reflectivity of the Cu:Co:KNSBN crystal is two time higher than that of KNSBN crystal. Zn:Fe:LiNbO3 and Cu:Co:KNSBN were used as storage element and self-pumping phase conjugate mirror, respectively, to make the holographic associative storage experiment. The excellent results were gained.
A series of Zn, Fe double-doped LiNbO3 crystals were grown by Czochralski technique with 0.015wt% of Fe2O3 and with different concentration of ZnO. The defect structures of the Zn:Fe:LiNbO3 crystals were studied by X-ray diffraction analyses and IR absorption spectra. The results indicated that the lattice constants of the Zn:Fe:LiNbO3 increase with the concentration of ZnO increasing in the crystals. The result indicates that the absorption peaks of the IR transmission spectra shift to the shorter wavelength with the increasing of concentration of ZnO. The optical damage resistance ability of the Zn:Fe:LiNbO3 crystals were investigated by straightly observing transmission facula distortion method, respectively. The results demonstrate that, compared with of Fe:LiNbO3, the optical damage resistance ability of the Zn (7.0mol%):Fe:LiNbO3 crystals is two orders magnitude higher than that of LiNbO3 crystal. 6.0mol% of ZnO is the perfect doping concentration.
Pr:LiNbO3 crystal can be used in two-color gated storage process for its special energy-level structure. Compared with other crystals used as volume holographic storage media, it has a great merit that an image recording does not erase the recorded one in multiplex storage process. But its photorefractive effect appears weaker than other crystals in the same conditions. We doped photorefractive sensitizing element Ce into Pr:LibNO3 to get Ce:Pr:LiNbO3 crystal with Czochralski method. The structure of crystals has been determined by X-ray powder diffraction method. The results indicate Pr:LiNbO3 and Ce:Pr:LiNbO3 keep the same structural characteristics as pure lithium niobate. In the absorption spectra of Pr:LiNbO3 and Ce:Pr:LiNbO3 samples with non-polarized light in wavelength of 300 - 900 nm, the absorption edge of Ce:Pr:LiNbO3 shifts to the red compared with that of Pr:LiNbO3. The diffraction efficiency, writing time and especially erasing time of Ce:Pr:LiNbO3 have been measured. We find that maximum diffraction efficiency of Ce:Pr:LiNbO3 has increased without at cost of decreasing the erasing time. The effect of doping ions on the optical properties of Ce:Pr:LiNbO3 crystal as holographic recording media has been studied systematically.
Nondoped and Ce2O3 doped near stoichiometric LiNbO3 (Ce:LiNbO3) single crystals were grown by the top-seeded solution method. The solution with [Li]/[Nb] ratio of 1 contained K2O component of 10.6 mol%(7.0 wt%). The ultraviolet-visible absoprtion spectra of the crystals were measured in order to analyze their structure. The photorefractive properties of stoichiometric LiNbO3 crystals were investigated and compared with congruent LiNbO3 crystal. Two-wave-coupling experiments shown that doped stoichiometric LiNbO3 crystals exhibited much larger photorefractive gain and faster response speed than congruent ones.
The congruent tri-doped Mg:Mn:Fe:LiNbO3 crystals have been grown by Czochralski method in air atmosphere. The crystal samples are reduced in Li2CO3 powder at 500°C for 24 hours or oxidized for 10 hours at 1100°C in Nb2O5 powder. Compared with as-grown Mg:Mn:Fe:LiNbO3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample or the reduced shifts to the red. The post-disposal, oxidation or reduction disposing has no effect on O-H vibration absorption peak in infrared region. In two coupling experiments we determine the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions. 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 145s and the biggest diffraction efficiency 67% among the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO3 crystals has been investigated.
Co-doping photo-refractive sensitive dopants CeO2, CuO and Fe2O3, Ce:Cu:Fe:LiNbO3 crystals were grown by Czochralski technique for the first time. The absorption spectra of the crystals were measured. The absorption edges of Cu:LiNbO3, Fe:LiNbO3 and Ce:Cu:Fe:LiNbO3 crystals shifted to red compared with LiNbO3 crystal and the absorption edge of Ce:Cu:Fe:LiNbO3 crystal shifted to red compared with Cu:LiNbO3 and Fe:LiNbO3 crystals. The exponential gain coefficients of Ce:Cu:Fe:LiNbO3 crystals with different thickness (0.2 mm, 0.4 mm, 1.0 mm and 2.0 mm) were measured. The exponential gain coefficient of thin crystal sample increased. The mechanism of the enhancement of the exponential gain coefficient of thin crystal was investigated.
Pr:LiNbO3 crystal can be used in two-color gated storage process for its special energy-level structure. Compared with other crystals used as volume holographic storage media, it has a great merit that an image recording does not erase the recorded one in multiplex storage process. But its photorefractive effect appears weaker than other crystals in the same conditions. We doped photorefractive sensitizing element Ce into Pr:LibNO3 to get Ce:Pr:LiNbO3 crystal with Czochralski method. The structure of crystals has been determined by X-ray powder diffraction method. The results indicate Pr:LiNbO3 and Ce:Pr:LiNbO3 keep the same structural characteristics as pure lithium niobate. In the absorption spectra of Pr:LiNbO3 and Ce:Pr:LiNbO3 samples with non-polarized light in wavelength of 300 - 900 nm, the absorption edge of Ce:Pr:LiNbO3 shifts to the red compared with that of Pr:LiNbO3. The diffraction efficiency, writing time and especially erasing time of Ce:Pr:LiNbO3 have been measured. We find that maximum diffraction efficiency of Ce:Pr:LiNbO3 has increased without at cost of decreasing the erasing time. The effect of doping ions on the optical properties of Ce:Pr:LiNbO3 crystal as holographic recording media has been studied systematically.
Doping CuO, Ce2O3 and ZnO in LiNbO3, Zn:Ce:Cu:LiNbO3 crystals are grown by the Czochralski method. The optical properties of the crystals are investigated, including photorefractive properties and spectrum properties. The photo scattering resistance ability of the crystal is one order of magnitude higher than that of Ce:Cu:LiNbO3 and the writing time of the crystal is as half time short as that of Ce:Cu:LiNbO3. The absorption spectra and infrared spectra of Zn:Ce:Cu:LiNbO3 were measured. The mechanism of the photo scattering resistance ability of Zn:Ce:Cu:LiNbO3 was investigated.
Lithium niobate crystals doped with the photorefractive sensitizing impurities of MnO and/or CuO have been grown by the Czochralski method. The crystals were treated with the oxidation or reduction. The absorption spectra of LiNbO3, Mn:LiNbO3, Cu:LiNbO3 and Mn:Cu:LiNbO3 were measured. For these four crystals, the absorption edge of pure LiNbO3 is at the shortest wavelength, and that of Mn:Cu:LiNbO3 is located at the longest wavelength. The exponential gain coefficient, diffraction efficiency, response time and phase conjugate reflectivity were measured. Mn:Cu:LiNbO3 has the excellent photorefractive properties and holographic storage properties.
Doping ZnO with the concentration of 3mol% and 7mol% in Ce:Mn:LiNbO3, respectively, Zn:Ce:Mn:LiNbO3 crystals were grown by Czochralski method. The optical damage resistance ability of crystals was measured. The optical damage resistance ability of Zn (7mol%):Ce:Mn:LiNbO3 crystal is two orders magnitude higher than that of Ce:Mn:LiNbO3 crystal. The exponentional gain coefficient, diffraction efficiency, response time and effective charge concentration were also obtained. The response speed of Zn(3mol%):Ce:Mn:LiNbO3 and Zn(7mol%):Ce:Mn:LiNbO3 crystal is two times and four times higher than that of Ce:Mn:LiNbO3, respectively. The mechanism of optical damage resistance ability of Zn:Ce:Mn:LiNbO3 crystal was researched.
The Tb:Fe:LiNbO3 and LiNbO3 crystals with vary Li/Nb ratio in the melt were grown by the top-seed solution growth (TSSG) method and Czochralski technique, respectively. Their Li/Nb ratios were calculated by the lattice parameters. The defect structure of the Tb:Fe:LiNbO3 and LiNbO3 with vary Li/Nb ratio in the melt crystals was studied by X-ray analyses and UV spectra. The results show that an increase of Li/Nb ratio in the melts leads to a decrease of the lattice constants, which is accompanied by an improvement of the LiNbO3 lattice structure because of diminishing concentration of intrinsic nonstoichiometric defects.
Doping CuO, Ce2O3 and In2O3 in LiNbO3, In:Ce:Cu:LiNbO3 crystals have been grown by the Czochralski method. The infrared spectra were measured and the mechanism of the violet shift of OH− absorption peak was investigated. In In:Ce:Cu:LiNbO3 crystal, Cu and Ce locate at the deep level and the shallow level, respectively. The two-photon holographic storage was realized in In:Ce:Cu:LiNbO3 crystal by using He-Ne laser as the recording light and ultraviolet light as the gating light. The recording time of In:Ce:Cu:LiNbO3 is 30 min, which is 10 min shorter than that of Ce:Cu:LiNbO3.
Doping Pr6O11 and Fe2O3 in LiNbO3, Pr:Fe:LiNbO3 and Pr:LiNbO3 have been grown by the Czochralski method. The lattice constants of the crystals were measured by the x-ray diffraction spectra. The absorption spectra of the crystals show that the absorption edge of Pr:LiNbO3 and Pr:Fe:LiNbO3 shifts to red in comparison with that of LiNbO3,and that of Pr:Fe:LiNbO3 has the most shifting level, which indicates that Pr:Fe:LiNbO3 has the high sensitivity. The diffraction efficiency of Pr:Fe:LiNbO3 was obtained as high as 63% by the two-wave coupling light path.
Ce:Co:SBN, Ce:SBN and Co:SBN crystals have been grown by Czochralski method with CeO2 and Co3O4 as dopants in air atmosphere. With these crystals as holographic storage media, the diffraction efficiency, response time and phase conjugate reflectivity are measured. The Ce:Co:SBN crystal exhibits better properties than SBN crystal and especially its diffraction efficiency is up to 70%. The Ce:Co:SBN crystal is used as holographic storage media to realize highly effective association storage in four-wave-mixing-frequency path with Zn:Fe:LiNbO3 crystal as feedback threshold element.
Mg:Fe:LiNbO3, Ce:Fe:LiNbO3 and Fe:LiNbO3 crystals were grown by the Czochralski method. The absorption spectra of these crystals were measured. It is shown in the results that the absorption edge of Mg:Fe:LiNbO3 shifts to violet while that of Ce:Fe:LiNbO3 shifts to red in comparison with that of Fe:LiNbO3. In the measurement of the photo scattering resistance ability of Fe:LiNbO3 and Mg:Fe:LiNbO3, it is found that the photo scattering resistance ability of Mg:Fe:LiNbO3 is two orders of magnitude higher than that of Fe:LiNbO3. The four wave mixing properties, such as the phase conjugate reflectivity and the response time, of the crystals were obtained. Among the three crystals, Ce:Fe:LiNbO3 has the largest phase conjugate reflectivity, and Mg:Fe:LiNbO3 has the shortest response time. Using Mg:Fe:LiNbO3 crystal as the storage material and Ce:Fe:LiNbO3 as phase conjugate reflector, the associative storage was realized.
Er:LiNbO3 and Mg:Er:LiNbO3 crystals were grown by the Czochralski method. All of crystals were possessed with polarization. In order to investigate the mechanism of OH absorption peak shift, the infrared absorption spectra of the crystals were measured. The absorption edge of ultraviolet-visible absorption spectrum of Mg:Er:LiNbO3 crystal showed a shift towards shorter wavelength. The fluorescence spectra of the crystals were investigated. The laser vibrate of Mg:Er:LiNbO3 crystal was realized easily at 1.54 micrometers , 0.887 micrometers and 0.5 micrometers . Benzoic acid was used as proton transfer reagent to make the waveguide substrate. By using the holograph method, the photodamage resistance ability and the enhance mechanism of the Mg:Er:LiNbO3 crystal waveguide substrate was measured.
Nondoped, Fe2O3 and Eu2O3-codoped near stoichiometric LiNbO3(Eu:Fe:LiNbO3) single crystals were grown by the top-seeded solution method. The solution with [Li]/[Nb] ratio of 1 contained K2O component of 10.6mol%(7.0wt%). The ultraviolet-visible absorption spectra, infrared absorption spectra of the crystals were measured in order to analyze their structure. The photorefractive properties of stoichiometric LiNbO3 crystals were investigated and compared with congruent LiNbO3 crystal. Two-wave-coupling experiments shown that doped stoichiometric LiNbO3 crystals exhibited much larger photorefractive gain and faster response speed than congruent ones.
The pure congruent LiNbO3, Er:LiNbO3 and Zn,Er- codoped Li-rich LiNbO3 crystals were grown by Czochralski method. In order to analyze their structure, the X-ray diffraction method, ultraviolet-visible absorption spectra and infrared absorption spectra of the crystals were investigated. The photo damage resistance ability of the crystals was measured. The Zn,Er-codoped Li-rich lithium niobate crystals showed a decrease in lattice constant values, a shift in absorption edge of ultraviolet-visible absorption spectra towards shorter wavelength, and increase in OH- absorption peak of infrared absorption spectra towards longer wavelength, and three orders of magnitude increase in phtorefractive damage resistance compared to congruent LiNbO3 crystal.
Doping ZnO and Ga2O3 in LiNbO3 crystal, the Zn:Ga:LiNbO3 was grown by Czochralski method. The IR transmission spectra and the photon damage resistance ability of the LiNbO3 and Zn:Ga:LiNbO3 crystal were measured. The proton exchange technology was used to make the LiNbO3 and Zn:Ga:LiNbO3 crystal waveguide substrates. The m-line method was taken to study the photo damage of waveguide substrate. We observed that the threshold of Zn:Ga:LiNbO3 is above two magnitude higher than that of Mg:LiNbO3. Zn:Ga:LiNbO3 crystal is better performance than LiNbO3 crystal.
In2O3 and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Fe:LiNbO3 crystals. The light scattering ability resistance, exponential gain coefficient, diffraction efficiency and response time of the crystals were measured. The light scattering ability resistance and response time of In:Fe:LiNbO3 is one magnitude higher than Fe:LiNbO3. In:Fe:LiNbO3 was used as storage element to make the large capacity holographic storage and the holographic associative storage reality. The excellent results were gained.
Zn, Fe:LiNbO3 crystal, with fine photorefractive properties, has been grown by Czochralski technique. Its response time was measured to be about ten seconds, the diffraction efficiency to be higher than 70 percent. Employing Zn, Fe:LiNbO3 as a holographic record media, another photorefractive crystal Cu:KNSBN as a self-pump phase conjugate mirror, the double-exposure interferometry has been studied in this paper.
Doping a little Fe2O3 and Tb4O7 into LiNbO3, the double-doped crystal LiNbO3:Fe,Tb was grown by Czochralski method. Its diffractive efficiency and the four-wave mixing phase conjugate reflectivity were measured to be the similar to the single-doped LiNbO3: Fe crystal. But the response time of the double-doped crystal was measured to be tens seconds, showing a great improvement comparing with LiNbO3: Fe. The mechanism of the results was discussed by measuring and calculating the values of the photoconductivity.
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