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Cracking process at lineages during the Czochralski (CZ) growth of 36°-RY lithium tantalate (LiTaO3) single crystals was examined. Twin lamellae on ( 1 ¯ 012 ) and ( 1 1 ¯ 02 ) were generated at lineages beneath the –Z’ surface of the ingots, via the dissociation of the dislocations composing the lineages. Two kinds of twin lamellae grew with the CZ growth towards the bottom of the ingots, forming the intersections nearly parallel to the growth direction. Cracking occurred at the intersections with developing the twin lamellae. The twinning accompanied with cracking took place when the diameter of the ingots was suddenly decreased. It is hypothesized that the decrease was introduced by an accidental fluctuation of growth temperature, and therefore, radial tensile stresses needed for twinning would be applied at the circumference of the ingots.

Patterned ferroelectric domains and domain selective etching of the patterned domains can provide ferroelectrics-based photonic crystals. In this paper, electron-beam has been applied to switch domains in LiNbO3 (LN) and LiTaO3 (LT) crystals. The complex dynamics of interaction of beam electrons with the crystals has been highlighted. Based on this research, an improved e-beam domain patterning technique utilizing resist covering is successfully applied to switch domains in a z-cut 1 mol% MgO-doped stoichiometric LN at room temperature.

Pure and MgO (0.5. 0.7 and 1 mol%)-doped near-stoichiometric lithium tantalate (near-SLT) crystals of 4-in diameter have been grown from off-stoichiometric melt using a double crucible. The grown crystals are free from cracks and twins. The addition of MgO increases the Curie temperature. SLT crystals with 0.7 mol% or more MgO doping concentrations showed enhanced optical damage resistance. The ordinary ray refractive indices in MgO-doped SLT crystals are slightly lower than the corresponding index of non-doped crystal. On the other hand, the extraordinary ray index of SLT is unaffected upon MgO doping. Periodically poled structures of 8 μm period have been fabricated over a length of 40 mm for 532 nm green generation through quasi phase matching.

The continuous-wave and acousto-optical Q-switched pulse laser properties of diode-pumped Nd:YAG crystal operating at 946 nm formed with a simple plane–plane cavity have been studied. Extra-cavity single-pass quasi-phase matching (QPM) frequency doubling with periodically poled LiTaO3 (PPLT) as the nonlinear crystal yielded a maximum output power of 66 mW at 473 nm with an overall optical to optical efficiency of 14.2% from 946 to 473 nm. Our result proves that this scheme is of practical value for the construction of a blue all-solid-state laser.

Near-stoichiometric LiTaO 3 single crystals, 80 mm in diameter and 25–30 mm in length, were grown by conventional Czochralski technique using radio-frequency heating and automatic control system. Two compositions of the starting melt were used, containing accordingly 58 and 60.5 mol% Li 2 O. The chemical composition of the grown crystals was estimated by measuring their coercive field to be 49.75–49.8 and 49.93–49.97 mol% Li 2 O for these two starting melts.

Off-centered top-seeded solution growth (TSSG) method is demonstrated as an effective and simple way to generate controlled composition modulation in potassium lithium tantalate niobate (KLTN) single crystals. The changes in concentration were measured by differential interference contrast (DIC) microscopy. Large length with periodic modulations ranging from 1 to 5 μm in period was grown along a KLTN sample with period dispersion lower than 2%.

Optical-quality near-stoichiometric lithium tantalate (SLT) crystals doped with Nb were grown by top seeded solution growth technique using induction-heating system. The crystalline wafers were subjected to optical transmittance studies and coercive field measurements. The optical transmittance spectra of doped crystals show a shift in the absorption edge towards longer wavelength side. A change in Curie temperatures with respect to doping concentrations of Nb has been observed. Hysteresis measurements reveal that the coercive field value increases for increasing niobium concentration. It has also been observed that there is a significant increase in the internal field value for Nb-doped SLT crystals.

Lithium tantalate (LiTaO 3 ) single crystals having different Li/Ta ratios were grown by using conventional and double crucible Czochralski method. The grown crystals appeared to have mole percent of Li 2 O ranging from 45.5 to 50 mol%. We analyzed the real composition with ICP method and measured the Curie temperatures (T c ) with DTA method. The relationship between T c and the mole percent of Li 2 O in LiTaO 3 crystals was derived. The transmission spectra and refractive indices were measured. The refractive indices measured by prism coupler were analyzed in terms of single-term Sellmeir parameters.

Single crystal fibers of K 3 Li 2 (Ta,Nb) 5 O 15 (KLTN) have been grown using micro-pulling-down technique. Crystals were produced from the melts containing 0–10 mol% of Ta 2 O 5 . Composition characterization was made by electron-probe microanalysis. Fast growth rates (about 0.5 mm/min) were found allowed preparation of macro defect free KLTN crystals with constant Ta : Nb cation ratio and segregation coefficients of Ta and Nb close to unity.

A new liquid-phase epitaxy technique for achieving selective three-dimensional growth with controlled ferroelectric-domain structures is proposed utilizing the “edge-growth” phenomenon and poling selectivity depending on the substrate-surface orientation. LiNb 1− x Ta x O 3 thin films with periodically switching spontaneous polarization were successfully formed on X -cut LiNbO 3 substrates by modulating the surface orientation.

LiNb 1− x Ta x O 3 epitaxial films, which were grown on LiNbO 3 substrates at various growth temperatures by the liquid-phase epitaxial method, were characterized using X-ray rocking curves, diffraction-space maps and absolute lattice constants. The films had relaxed structures regardless of the growth temperature, and the density of the dislocations due to the lattice mismatch between the films and the substrates increased with increasing growth temperature. Therefore, the crystallinity of the films became poor with increasing growth temperature.

The tantalum composition (x) in LiNb1−xTaxO3 solid-solution films grown on LiNbO3 by liquid-phase epitaxy can be precisely controlled by changing the growth temperature. The composition of the film was found to be nearly stoichiometric (Li(Nb + Ta) = 1) based on electron probe microanalysis and X-ray rocking curve analysis. The second-harmonic generation phase-matching wavelength becomes longer by substituting Ta for Nb in LiNbO3.

LiNbO 3 /LiNb 1-x Ta x O 3 multilayered films, which form an optical waveguide structure, were grown on a LiNbO 3 substrate by the liquid phase epitaxial method.

A three-dimensional finite element computer program for thermal stress analyses was developed to deal with the cracking of trigonal class 3m oxide bulk single crystals, such as lithium niobate (LN) and lithium tantalate (LT) during Czochralski growth. A tensor transformation technique was used to obtain the elastic constant matrix and thermal expansion coefficient vector corresponding to an arbitrary pulling direction. The anisotropy of the elastic constants and thermal expansion coefficients as well as their temperature dependence were considered in the program. Using this program, we performed thermal stress analyses of LN bulk single crystals with three types of temperature distribution or the shape of crystal-melt interface. The analyses were performed both for the pulling directions of the a-axis [100] and c-axis [001]. The results show that the thermal stress is very sensitive to the shape of the crystal-melt interface, and that the thermal stress is lower in the c-axis pulling than in the a-axis pulling. The relation between the thermal stress and the cracking and the quality of a bulk single crystal is also discussed.

We report the growth of doped potassium lithium tantalate niobate (KLTN) crystals and characterization of their physical properties. The top seeded solution growth method is described. The specifics of a particular KLTN:Cu growth are presented, and the resultant crystal is described. The dielectric properties are compared to those of KTN; the addition of lithium is demonstrated to change the character of the phase transitions as well as increase the transition temperature. Phase diagrams for the KLTN system are illustrated as a function of lithium and niobium concentration.

Potassium lithium tantalate niobate K 3 Li 2 (Ta x Nb 1− x ) 5 O 15 crystal was grown by top-seeded solution growth method. Crack-free crystal in a size of 4×5×15 mm 3 was obtained. The as-grown crystal was demonstrated to be in a multidomain state by chemical etching. Single domain crystal was obtained by applying a DC electric field at an elevated temperature. The crystal was used to double the frequency of 1.06 μm of the Nd : YAG laser at room temperature by non-critical phase matching.

Lithium tantalate (LiTaO 3 ) crystals were grown from molybdenum crucibles by the Czochralski and Stepanov techniques. Physical constants of the LiTaO 3 melt, such as density and capillary constant, were determined. The quality of the crystals grown from molybdenum crucibles was practically identical to that for iridium crucible material.

A sensitive lever mechanism capable of accurately monitoring the weight of a growing, rotating crystal boule is described. The low noise weight data can be processed by an analog control system or an automatic, digital, adaptive control system to grow a boule to a programmed diameter. The operational success depends on the frictionless mechanical multiplication of the load and electronic expansion of the transducer response. The resulting monitoring sensitivity has produced lithium tantalate, lithium niobate and neodymium gallium garnet boules of 22 mm diameter with ±0.4 mm variation over the length of the boule. The mechanism is schematically shown incorporated in a newly designed crystal puller to illustrate its functional uniqueness and potential adaptability to crystal pulling systems of other types.