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.
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.
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.
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: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.
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.
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.
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 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 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.
Doping Eu2o3 and CeO2 in LiNbO3, Ce:Eu:LiNbO3 crystal was successfully grown by the Czochralski method. The lattice constants of Ce:Eu:LiNbO3 were calculated. For the reason of volume compensation effect, that lattice constants of Ce:Eu:LiNbO3 were smaller than that of Ce:LiNbO3 and Eu:LiNbO3. It was found in the absorption spectra that the absorption band of Ce:Eu:LiNbO3 has the most red shift, and this phenomenon was explained. The response time of 32s, refractive efficiency of 75% and exponential gain coefficient of 22cm(superscript -1 of Ce:Eu:LiNbO3 was obtained by the holographic method. In the end, using Ce:Eu:LiNbO3 as storage medium, the holographic associative storage was realized and the clear and integrated retrieval graph was obtained.
Nd:YVO4 crystal was successfully grown by the Czochralski method. The crystal growth process was described in detail: The transmittance and emission spectra of Nd:YVO4 crystal have been measured. The wavlength of the main absorption peak is centered at 808.97nm, and that of the emission peak is centered at 1064nm. The fluoresence lifetime of (formula available in paper).
In this research, Czochralski method was used to grow Zn:In:LiNbO3 crystal. The lattice constants, ultra- visible absorption spectra, infrared absorption spectra and photodamage resistance ability of the crystal were measured. The photodamage threshold of LiNbO3 and Zn:In:LiNbO3 crystal waveguide substrate were investigated by the m-line method. It is found that the higher the concentrations of In and Zn were doped, the more the absorption band of crystal was shifted to short wave. The OH absorption peak of Zn(3mo1%):In(2mo1%):LiNbO3 and Zn(3mo1%):In(1mo1%):LiNbO3 crystal was located at about 3484 cm-1, and that of Zn(3mo1%):In(3mo1%):LiNbO3 crystal was located at about 3515 cm-1. The photodamage resistance ability of Zn(3mo1%):In(2mo1%):LiNbO3 crystal was two orders of magnitude higher than that of LiNbO3 crystal. The photodamage threshold of LiNbO3 crystal waveguide substrate and Zn:In:LiNbO3 crystal waveguide substrate were 5x103J/cm2 and 1x106J/cm2, respectively.
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.
The preparation of polycrystalline GaAs films by using electrodeposition technology is described. Influences of electrodeposition parameters on the quality of films were discussed, such as the current density, the relative concentration of ions, the value of pH of the electrolyte. On the basis of observing the micrographs, we have measured the chemical composition, microstructure and parameters of the energy band of the films. The result show that the composition of the films deposited is Ga0.9946 As1.0054, and the direct gap nature of the deposited material, its band gap is 1.40eV.
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.
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