Hydrogen in lithium niobate

Cabrera, Jesús Hernández; Olivares, J.; Carrascosa, M.; Rams, J.; Muller, Richard E.; Diéguez, E.

doi:10.1080/00018739600101517

Cited by 165 publications

(113 citation statements)

References 174 publications

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“…The experimental data have usually been analyzed by employing simplified, phenomenological models 58,[166][167][168] with only rare attempts 169 to analyse and supplement them by first principles theoretical calculations. Some information on dynamics and kinetics, i.e., activation barrier height and rate constants, has been deduced from analysing the temperature dependent of ionic conductivity 170 and IR spectra 64 as well as holographic scattering, 171 while 1 H NMR measurements have been employed to find the location of protons within the crystal lattice.…”

Section: Oh 2 Ionsmentioning

confidence: 99%

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

Lengyel

Péter

Kovács

et al. 2015

Applied Physics Reviews

103

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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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Section: Oh 2 Ionsmentioning

confidence: 99%

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

Lengyel

Péter

Kovács

et al. 2015

Applied Physics Reviews

103

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“…Therefore, it now becomes clear that the Zn-diffusion process is, in fact, an ion-exchange process (Zn↔2Li) from the vapor phase in the same way as H and Li are exchanged when LiNbO 3 is inmersed into a weak acid. 16 No oxygen leaks have been detected in our measurements. The stoichiometry data for the outermost layer can be satisfactorily fitted to a mixture LiNbO 3 /ZnNb 2 O 6 with composition profiles shown in Fig.…”

mentioning

confidence: 68%

Characterization of surface layers in Zn-diffused LiNbO3 waveguides by heavy ion elastic recoil detection

Espeso-Gil

Garcı́a

Agulló‐López

et al. 2002

Applied Physics Letters

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The surface layers formed in LiNbO 3 waveguides, fabricated by Zn diffusion from the vapor phase, have been investigated by time of flight elastic recoil detection analysis using 127 I ions. The key features of this technique, simultaneous profiling of all ions and a depth of analysis Ͻ1 m, have allowed a detailed and quantitative characterization of the surface layers. The Zn diffusion into LiNbO 3 can be understood as a 2Li↔Zn exchange process. As a consequence, an outermost layer of several hundreds of nanometers is formed, consisting of LiNbO 3 and ZnNb 2 O 6 phases showing complementary profiles. A good correlation has been found between the composition profiles and the optical waveguiding behavior. After thermal annealing of the waveguides, a thinner layer containing a uniform mixture of ZnO and LiNbO 3 is generated followed by a transition to a graded solid solution of Zn into LiNbO 3 . © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1506405͔ Different methods are available for the fabrication of good-quality low-loss waveguides in LiNbO 3 . In particular, Ti diffusion, performed at 900-1100°C, has been commercially implemented for many years for the fabrication of a variety of integrated optics devices. 1 Unfortunately, optical damage ͑photorefractive effect͒ severely impairs the use of these waveguides for high-power density applications such as lasers and nonlinear optical devices in the visible range. Several alternatives to Ti diffusion have been put forward and are being developed. One promising approach is Zn diffusion from the vapor phase, 2 from a ZnO source, 3 or by liquid-phase epitaxy. 4 In the first procedure, the diffusion temperature is much lower ͑550-800°C͒ than that for Ti diffusion and therefore it is free of many problems derived from the high temperature processing. The Zn-doped material presents good crystallinity, transparency, 5 and resistance to laser damage. 6 At the same time, they preserve the high electrooptic coefficients 7 and the ferroelectric domain structure of the LiNbO 3 substrate. 8 The fabrication process involves two steps: the diffusion of Zn from the vapor phase at 500-700°C, followed by an annealing step performed at 800-900°C. Some laser and nonlinear optical devices have been already implemented on Zn-doped waveguides. 9,10 However, the physical characterization of the waveguides is still defficient. Optical experiments have suggested the formation of a multilayer structure with a thin low-index film at the surface, 11 although a direct experimental confirmation is lacking. In fact, the techniques used so far are either insensitive to these surface layers or not quantitative enough to provide a detailed and reliable picture.The purpose of this work has been to apply the potential of the time of flight elastic recoil detection analysis ͑TOF-ERDA͒ method 12 using heavy 127 I ions to determine the near-surface profiles of all relevant atom species. The main advantage of this technique is that the information for all elements is retrieved in the same experimen...

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“…As it can bee seen from Fig. 1, at room temperature, the spectrum represents the absorption band caused by OH − stretching vibrations characteristic for congruent LiNbO 3 [2][3][4][5][7][8][9][10]. Maximum of the band lies at around 3480 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

“…[2,9] it was shown that incorporation of hydrogen in the crystal can be achieved by means of crystals annealing in vapour-rich atmosphere at about 670 K. In Refs. [2,3,9] the experiments of hydrogen removing from the crystal were held during its annealing in vacuum at about 670 K. The authors consider that in this case H + -ions leave the crystal in forms of H 2 O molecules and, at the same time, crystal reduces and obtains dark color. After that one can make LiNbO 3 crystal transparent and free from hydrogen impurities by annealing it in pure oxygen atmosphere avoiding ingress of moisture.…”

Section: Introductionmentioning

confidence: 99%

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In situ Investigation of OH^-Absorption in LiNbO₃and LiNbO₃:MgO Crystals during Reducing/Oxidizing Annealing

Sugak

Zhydachevskii

et al. 2010

Acta Phys. Pol. A

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The work presents experimental results of an in situ investigation of the OH − absorption in pure and MgO-doped LiNbO3 crystals during reducing (95% Ar + 5% H2) and oxidizing (O2) high-temperature treatments in the temperature range from room temperature to 820 K. The absorption spectra measured in situ at high temperatures in reducing/oxidizing atmospheres have been analyzed. The origin of the changes in optical absorption caused by heating of the crystal is discussed in terms of the OH-bonds orientation change.

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Hydrogen in lithium niobate

Cited by 165 publications

References 174 publications

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

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

Characterization of surface layers in Zn-diffused LiNbO3 waveguides by heavy ion elastic recoil detection

In situ Investigation of OH^-Absorption in LiNbO₃and LiNbO₃:MgO Crystals during Reducing/Oxidizing Annealing

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Hydrogen in lithium niobate

Cited by 165 publications

References 174 publications

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

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

Characterization of surface layers in Zn-diffused LiNbO3 waveguides by heavy ion elastic recoil detection

In situ Investigation of OH-Absorption in LiNbO3and LiNbO3:MgO Crystals during Reducing/Oxidizing Annealing

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In situ Investigation of OH^-Absorption in LiNbO₃and LiNbO₃:MgO Crystals during Reducing/Oxidizing Annealing