Cr3+Sr0.6Ba0.4Nb2O6 single crystals for photorefractive applications (original) (raw)
Related papers
Doping-Dependent Properties in Photorefractive Congruent Sr x Ba 1- x Nb 2 O 6 :Ce, Cr Crystals
Ferroelectrics, 2004
The photorefractive properties of Sr x Ba 1−x Nb 2 O 6 (SBN, congruent composition x = 0.61) can be enhanced by doping with suitable polyvalent ions like Ce or Cr. We report on optical absorption measurements in the UV-FIR region and on dielectric measurements in the temperature range 2-400 K as a function of the dopant concentration. The addition of a third doping component, photorefractive not active Li-ions, did not raise the ferroelectric phase transition temperature T c .
Two types of SBN crystals were grown and analyzed for their spectroscopic and dielectric properties: Sr 0.33 Ba 0.67 Nb 2 O 6 : Cr and Sr 0.58 Ba 0.42 Nb 2 O 6 : Cr, Yb. The absorption and EPR spectra show the presence of Cr 3+ at interstitial ions beside the ions substituted for Nb 5+ . Unexpectedly, Yb 3+ has not entered to the Sr 0.58 Ba 0.42 Nb 2 O 6 : Cr crystal at Nb 5+ octahedral sites. The crystals differ significantly each other especially for their dielectric properties mainly due to stoichiometry. The former crystal exhibits ferroelectric phase transition at about 378K, while the latter at 340K. We have found spontaneous polarization being equal to 2,44 µC/cm 2 (SBN:33:Cr) and to 1 µC/cm 2 (SBN:58:Cr:Yb).
Optics Letters, 1990
We present what is to our knowledge the first report on the photorefractive properties of Rh-doped Sr 0 o 6 Ba 0. 4 Nb 2 06 and experimental results showing a reduction of the photorefractive two-beam coupling response time by more than an order of magnitude with an external dc field of 10 kV/cm. Doped SrU. 6 BaO. 4 Nb 2 0 6 (SBN:60) using Fe, Ce, Ce-Ca, and Cr has been shown to be photorefractive with high gain and real-time response. 1-3 Cr-doped SBN:60 crystals have been shown to have response times of near 0.2 sec at 0.25 W/cm 2 , which is approximately an order of magnitude faster than what was measured in Ce-doped samples, but their photorefractive gain ranged from 3 to 6 cm-1 compared with more than 10 cm-1 in Ce-doped SBN:60. Applying an electric field
Near-infrared photorefractivity in Cr-doped potassium sodium strontium barium niobate single crystal
Applied Physics A Solids and Surfaces, 1992
We report on the photorefractive properties of a Cr-doped (KI-zNaz)2A-2 (SrvBal_y)z_ANbt0030 (z = 0.586, y = 0.659, A = 1.12) single crystal in the near-infrared spectrum. The sample exhibits photorefracitivity for wavelengths up to at least 840nm where the steady-state two-beam coupling gain is found to be larger than 2cm -~. Photorefractive gain and decay rate are measured as a function of wavelength, grating spacing and intensity. The wavelength dependence of gain fluctuations in two-beam coupling are also measured.
Journal of the Optical Society of America B, 1993
We determine several photorefractive properties of undoped, Cr-doped, and Cu-doped (KyNali) 2 , (Sr.Bal,-),-. Nb 2 O 6 (KNSBN) crystals by means of two-beam coupling measurements. An elemental analysis of the crystals to determine their compositions and impurities is also performed. It is found that two-beam coupling gain of the Cr-doped KNSBN at 514.5 nm is enhanced by -10 times that of the undoped KNSBN, while its response speed remains substantially unchanged. Longer-wavelength photorefractivity is also observed in the Cr-doped KNSBN. Quasi-periodic oscillations of the probe-beam intensity in the two-beam coupling experiment are observed in the Cu-doped KNSBN.
Applied Physics Letters, 2001
We demonstrate a possibility to modify photorefractive properties of a ferroelectric crystal by means of controlling the ferroelectric phase transition. This is shown by an example of co-doping a photorefractive SBN-0.61:Ce crystal with a nonphotorefractive La impurity, which strongly lowers the ferroelectric phase transition and in turn drastically enhances the linear electrooptic coefficients. The observed low coercive fields enable us to build in SBN:͑CeϩLa͒ a reproducible fast switching of the energy transfer direction. This is done by an electric field switching which changes the sign of the two-beam coupling gain factor ⌫.
Photorefractive properties of Ce-doped (BaSr)_6Ti_2Nb_8O_30 crystals
Optics Letters, 1992
The photorefractive effect is demonstrated in single crystals of ferroelectric Ce-doped (BaSr)6Ti2Nb8030 for the first time to our knowledge. The maximum intensity gain, measured by two-beam coupling at a 488-nm wavelength, was F-20 cm-'. The photorefractive time response, also measured from beam coupling, was determined to be 0.1 s at an incident intensity of I = 1 W/cm 2. Ce-doped (BaSr)6Ti 2 Nb8s3O (BSTN), which has a Ba-to-Sr ratio of 2:1, is a new material with a crys
Large photorefractive coupling coefficient in a thin cerium-doped strontium barium niobate crystal
Journal of the Optical Society of America B, 1991
Photorefractive two-beam-coupling coefficients are measured and compared in thin and thick cerium-doped strontium barium niobate crystals fabricated from the same boule. For extraordinary polarization, the thin sample exhibits an intensity coupling coefficient as high as 45 cm-', whereas the highest coefficient measured in the thick sample is only -14 cm-'. The measured dependences of two-beam coupling on beam-crossing angle, pump-probe beam ratio, and wavelength are compared in these thin and thick crystals; also, comparisons are made in photorefractive response times and optical absorption. We infer that the measured coupling coefficients in the thin sample are more reliable, and we attribute the reduced coupling coefficients in the thick sample to beam fanning. Beam fanning is incorporated into a coupled-wave theory to predict the reduced coupling coefficients in the thick sample, along with the dependence of the coupling on the pump-probe beam ratio.
Temperature dependence of PL and EPR spectra of Sr0.33Ba0.67Nb2O6:Cr (0.02mol%) single crystals
Journal of Crystal Growth, 2014
a b s t r a c t Sr 0.33 Ba 0.67 Nb 2 O 6 :Cr (0.02 mol%) single crystals have been prepared by the Czochralski method. They were investigated by electron paramagnetic resonance and photoluminescence in a temperature range of 3-300 K. The EPR signal shows at least two magnetically non-equivalent centers. We have calculated temperature and angular dependences of the EPR spectra, and spin Hamiltonian parameters for both centers. Low temperature photoluminescence spectra reveal emission bands at 765 and 824 nm in addition to an intense emission band at 537 nm. From the EPR and PL analysis, it is suggested that two different Cr-associated defect centers are present in this crystal.