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A series of Mg2+/Er3+-codoped congruent LiNbO3 crystals were grown by Czochralski method from the growth melts containing 0.5 mol% Er2O3 while varied MgO content from 0.0 to 7.0 mol%. The unclamped electro-optic coefficients γ13 and γ33 of these crystals were measured by Mach-Zehnder interferometry. Two different voltage-applying schemes were adopted: one is the DC voltage applied to the crystal via Al films coated onto crystal surfaces and another is via a pair of external Cu slab electrodes. The coefficients measured by the two schemes show similar strong dependence on Mg2+ concentration. The dependence is non-monotonous, dramatic, and unusual, and reveals the features of two Mg2+ concentration thresholds of optical damage: one in the Mg2+ concentration range of 1.2-2.0 mol% (in crystal) and another in 4.5-5.0 mol%. Around the threshold the electro-optic coefficient decreases abruptly at first and then recovers quickly, and the coefficient drops by >20% (12%) at the first (second) threshold, which exceeds the error 3% considerably. The dramatic behavior is qualitatively explained on the basis of the EO coefficient model of LiNbO3 and the defect structure model for Mg2+-doped LiNbO3. [ABSTRACT FROM AUTHOR]

Ti-diffused LiTaO 3 strip waveguide was fabricated by in-diffusion of 8-μm-wide, 100-nm-thick Ti-strip at 1300 °C for 6 h in wet O 2 atmosphere. Its composition, surface morphology, lattice parameter, optical properties and Ti profile characteristics were fully characterized. It is shown that the waveguide is in the congruent composition environment. The waveguide surface caves in ∼70 nm below the crystal surface due to Ti-induced lattice contraction, which is verified by X-ray single-crystal diffraction. Optical characterizations show that the waveguide well supports both TE and TM single-mode propagation at the 1.5 μm wavelength, is polarization-insensitive, and has a loss of 0.4 (0.3) dB/cm for the TM (TE) mode. Secondary ion mass spectrometry analysis shows that the Ti profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of the waveguide. [ABSTRACT FROM AUTHOR]

Clamped and unclamped electro-optic coefficients γ 13 and γ 33 of In 3+ /Er 3+ -codoped LiNbO 3 crystals, which were grown by Czochralski method from the melts containing 0.5 mol% Er 2 O 3 while varied In 2 O 3 contents of 0.0, 0.5, 1.0 and 1.5 mol%, were measured by Mach-Zehnder interferometry. The results show that In 3+ /Er 3+ codoping does not cause change of γ 13 and γ 33 , and both γ 13 and γ 33 can be regarded as unchanged in the studied In 3+ concentration range of 0–2.6 mol% (in crystal) within the experimental error of 3%. The small doping effect is desired in light of the electro-optic application of the crystal. A qualitative, comprehensible explanation for the small effect is given on the basis of the EO coefficient model of LiNbO 3 and doping effect on the defect structure of LiNbO 3 . [ABSTRACT FROM AUTHOR]

A series of singly Er 3+ -doped and doubly In 3+ /Er 3+ -doped congruent LiNbO 3 crystals were grown by Czochralski method. The Er 3+ -only doped crystals were grown from the growth melts doped with different concentrations of Er 2 O 3 up to 1 mol%, and the In 3+ /Er 3+ -codoped crystals from the melts doped with fixed 0.5 mol% Er 2 O 3 while varied In 2 O 3 contents of 0.0, 0.5, 1.0 and 1.5 mol%. The electro-optic coefficients γ 13 and γ 33 of these doped crystals were measured by Mach-Zehnder interferometry. Both clamped and unclamped coefficients were measured. The results show that both γ 13 and γ 33 reveal small Er 3+ and In 3+ doping effects. In the Er 3+ -only doping case, γ 13 almost does not change within the experimental error of 3%, γ 33 reveals a degradation tendency with a rise in Er 3+ doping level, but the degradation is no more than 5% in the considered Er 3+ concentration range 0–3.0 mol% (in crystal). In the In 3+ /Er 3+ -codoping case, both γ 13 and γ 33 can be regarded as unchanged in the studied In 3+ concentration range of 0–2.6 mol% (in crystal) within the error. The small Er 3+ or In 3+ doping effect is desired in light of electro-optic application of these crystals. It is qualitatively explained on the basis of EO coefficient model and doping effect on defect structure of LiNbO 3 . [ABSTRACT FROM AUTHOR]

Highlights • A mistake in previous paper Opt. Laser Technol. 88 (2017) 152–156] is corrected. • γ 33 and γ 13 were measured by two voltage-applying schemes: Schemes One and Two. • In the Scheme Two, a DC voltage is applied via Al films on crystal surfaces. • γ 33 and γ 13 measured by the Scheme Two are unclamped instead of clamped. Abstract We correct a mistake in the previous paper "Electro-optic properties of indium/erbium-codoped lithium niobate crystal for integrated optics" [Opt. Laser Technol. 88 (2017) 152–156]. The electro-optic coefficients γ 33 and γ 13 that were measured by applying a DC voltage to the crystal via the Al films coated onto the crystal surfaces are the unclamped instead of clamped coefficients. [ABSTRACT FROM AUTHOR]