Compositional uniformity in growth and poling of large-diameter lithium niobate crystals

Bordui, P. F.; Norwood, R. G.; Bird, C. D.; Calvert, G.D.

doi:10.1016/0022-0248(91)90009-t

Cited by 121 publications

(46 citation statements)

References 10 publications

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“…As congruent LiNbO 3 (cLN) was easily damaged, to provide more resistant optical components for laser applications, tailoring of key material parameters via stoichiometry control and/or doping by additives promoting optical damage resistant (ODR) behaviour in the visible-near infrared region, e.g., Mg, Zn, In, Sc, etc., 10 has been introduced. For producing stoichiometric samples, new techniques, including the preparation of stoichiometric wafers or fibers from cLN crystals by the vapor transport equilibration (VTE) method 11,12 as well as various solution growth techniques, have been applied. As the demand for pure and doped bulk stoichiometric LiNbO 3 (sLN) crystals kept increasing, efforts became concentrated on the development of crystal growth techniques, such as the continuous filling double crucible growth 13 and the high temperature top seeded solution growth (HTTSSG).…”

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confidence: 99%

Growth, defect structure, and THz application of stoichiometric lithium niobate

Lengyel

Péter

Kovács

et al. 2015

Applied Physics Reviews

105

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Owing to the extraordinary richness of its physical properties, congruent lithium niobate has attracted multidecade-long interest both for fundamental science and applications. The combination of ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as the strong photorefractive and photovoltaic effects offers a great potential for applications in modern optics. To provide powerful optical components in high energy laser applications, tailoring of key material parameters, especially stoichiometry, is required. This paper reviews the state of the art of growing large stoichiometric LiNbO 3 (sLN) crystals, in particular, the defect engineering of pure and doped sLN with emphasis on optical damage resistant (ODR) dopants (e.g., Mg, Zn, In, Sc, Hf, Zr, Sn). The discussion is focused on crystals grown by the high temperature top seeded solution growth (HTTSSG) technique using alkali oxide fluxing agents. Based on high-temperature phase equilibria studies of the Li 2 O-Nb 2 O 5 -X 2 O ternary systems (X ¼ Na, K, Rb, Cs), the impact of alkali homologue additives on the stoichiometry of the lithium niobate phase will be analyzed, together with a summary of the ultraviolet, infrared, and far-infrared absorption spectroscopic methods developed to characterize the composition of the crystals. It will be shown that using HTTSSG from K 2 O containing flux, crystals closest to the stoichiometric composition can be grown characterized by a UV-edge position of at about 302 nm and a single narrow hydroxyl band in the IR with a linewidth of less than 3 cm À1 at 300 K. The threshold concentrations for ODR dopants depend on crystal stoichiometry and the valence of the dopants; Raman spectra, hydroxyl vibration spectra, and Z-scan measurements prove to be useful to distinguish crystals below and above the photorefractive threshold. Crystals just above the threshold are preferred for most nonlinear optical applications apart holography and have the additional advantage to minimize the absorption even in the far-infrared (THz) range. The review also provides a discussion on the progress made in the characterization of non-stoichiometry related intrinsic and extrinsic defect structures in doped LN crystals, with emphasis on ODR-ion-doped and/or closely stoichiometric systems, based on both spectroscopic measurements and theoretical modelling, including the results of first principles quantum mechanical calculations on hydroxyl defects. It will also be shown that new perspective applications, e.g., the generation of high energy THz pulses with energies on the tens-of-mJ scale, are feasible with ODR-doped sLN crystals if optimal conditions, including the contact grating technique, are applied. V C 2015 AIP Publishing LLC.

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confidence: 99%

Growth, defect structure, and THz application of stoichiometric lithium niobate

Lengyel

Péter

Kovács

et al. 2015

Applied Physics Reviews

105

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“…The space-charge fields modulate the refractive index through the electro-optic effect. In this way, thick phase holograms can be recorded in LiNbO 3 . Normally, LiNbO 3 is grown from the congruent melt where the Li concentration c Li is not equal to the Nb concentration c Nb .…”

Section: Introductionmentioning

confidence: 99%

“…The relative Li content c Li /(c Li ϩ c Nb ) of congruently melting LiNbO 3 is ϳ48.4%, which is much smaller than the stoichiometric composition. 3 The photorefractive properties strongly depend on defects and impurities of the crystal. Doping with, e.g., iron or copper leads to an enlarged photorefractive effect.…”

Section: Introductionmentioning

confidence: 99%

“…However, besides varying the concentration of extrinsic defects, it is possible to influence the intrinsic defects. Due to the Li deficit of congruent LiNbO 3 , there exist a lot of Li vacancies and Nb Li (Nb on Li site) antisite defects. 7 The concentration of vacancies and antisites can be decreased with the help of a VTE (vapor transport equilibration) technique.…”

Section: Introductionmentioning

confidence: 99%

“…The Li ions are placed on vacancies or displace Nb Li ions, and the result is an increased Li content. Our interest is focused on the influence of a VTE treatment on the photorefractive properties of copper-doped LiNbO 3 because, up to now, the holographic properties of nearstoichiometric LiNbO 3 are not examined in detail. LiNbO 3 can easily be doped with copper by an in-diffusion technique because the diffusion constant for copper is more than 500 times higher than the diffusion constant for iron.…”

Section: Introductionmentioning

confidence: 99%

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Photorefractive properties of lithium and copper in-diffused lithium niobate crystals

et al. 2002

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Near-stoichiometric copper-doped lithium niobate crystals are fabricated by in-diffusion of thin layers of evaporated copper and a subsequent vapor transport equilibration treatment. The crystals are heated in a Li-rich atmosphere to increase the Li content. To determine the photorefractive properties, holographic as well as electrical measurements are performed. Saturation values of the refractive-index changes ⌬n S , bulk photovoltaic current densities j phv , photoconductivities ph , and holographic sensitivities S are measured for light intensities up to 10 4 W/m 2 . Comparison with experimental data of congruent crystals indicates that the specific photoconductivity is 15 times larger after a vapor transport equilibration treatment. The specific bulk photovoltaic coefficient ␤* is 2 times larger, refractive-index changes are 7 times smaller, and the holographic sensitivity is up to 4 times larger.

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