11115-95-0Relevant articles and documents
Influence of Nd:Zn codoping in near-stoichiometric lithium niobate
Babu Reddy, J. N.,Kamath, K. Ganesh,Vanishri, S.,Bhat, H. L.,Elizabeth, Suja
, p. 1 - 10 (2011/10/03)
Near-stoichiometric lithium niobate (SLN) crystals doped with up to 1.6 mol percent Zn and codoped with various Nd concentrations in the melt (0.2, 0.5, 0.9, and 1.5 mol percent) (Nd:Zn:SLN) are grown from 58.6 mol percent Li2 O using conventional Czochralski technique. Crystals are pulled at the rate of 0.35 mmh with seed rotation at 9 rpm. Concentrations of Zn and Nd in the crystal are varied by adding appropriate amounts of ZnO and Nd2O3 to the starting composition. Unit cell parameters of the grown crystals are calculated by Rietveld refinementmethod using FULLPROFF software. Domain structure studies are carried o ut by chemical etching followed by microscopic examination. Dielectric studies reveal the existence of piezoelectric resonance at high frequencies. Enhancement in dielectric constant and tan δ in Nd doped samples has been attributed to the space charge polarization. Nd doped samples exhibit reduction in the relative permittivity after oxygen annealing.Transmission spectra of Nd:Zn:SLN crystals in the UV region exhibit blu eshift in the cutoff wavelength. In Mid Infrared (MIR) region crystals doped with 1.6 mol percent Zn have shift in the OH absorption peak from 2873 to 2833 nm. Judd-Ofelt analysis carried out on the absorption spectra of codoped crystal yields the lifetime of 104 μs for the metastablestate 4F 3/2. The branching ratio for the electro nic transition from 4F 3/2 to 4I 1/2 is high compared to that for 4F 3/2 to I 132 4, indicating a higher emission cross section for the former transition. Laser damage threshold evaluated using 532 nm, 5 ns pulsed neodymium doped yttrium aluminum garnet laser, shows an increase by two orders of magnitude for crystals doped with 1.6 mol percent Zn. Photorefractive damage threshold for these crystals shows an enhancement of four orders of magnitude due to increase in the photoconductivity.