Zeliang Gao

Electro-optic properties of BaTeMo2O9 single crystal

The electro-optic (EO) properties of monoclinic BaTeMo2O9 (BTM) single crystals are studied using the interference technique by applying the external electric field. The measured room temperature free EO coefficients at 632.8 nm are 10.2 and 9.0 pm/V for γ12 and γ41, respectively. The EO effect (−12ni3γijE) of BTM is about three times as high as that of KH2PO4 (KDP) crystal, which makes it a very promising candidate for the EO applications.

Second order nonlinear properties of monoclinic single crystal BaTeMo2O9

The second order nonlinear optical properties of BaTeMo2O9 were studied by means of Maker fringe technology and the phase matching method. The value and relative sign of the second order nonlinear optical coefficients were obtained, with the largest being d31 = 9.88 pm/V. At 1064 nm, the crystal can support noncritical phase-matching, and the effective nonlinear coefficient is 10.3 pm/V for phase matching II at (90°, 62.8°) in the x0y plane. The relation between the second order nonlinear properties and the crystal structure is also discussed. All the results show that BaTeMo2O9 is a good candidate for nonlinear optical applications.

High efficient external resonator Raman laser based on the monoclinic single crystal BaTeMo2O9

In this paper spontaneous Raman spectra of monoclinic single crystals of BaTeMo2O9 (BTM) along the Z axis has been characterized, and a highly efficient stimulated Raman scattering laser operating at 1178 nm has been realized based on the BTM crystal. The Raman resonator possesses a threshold of 28 MW/cm2 at 1064 nm and a maximum output pulse energy of 19.2 mJ for the first-order Stokes with an optical-to-optical conversion efficiency of 48% and a slope efficiency of 61.2%. The largest optical-to-optical conversion efficiency can reach 50.4% at a pump energy of 28.8 mJ. Our experimental results demonstrate that BTM can be used as an excellent near and mid-infrared Raman laser material.

Investigation of the dielectric, elastic, and piezoelectric properties of Cs2TeMo3O12 crystals

The complete sets of dielectric, elastic, and piezoelectric constants of Cs2TeMo3O12 crystals at room temperature were determined by means of the resonant technique and impedance analysis. The piezoelectric strain constants d33 and d15 were on the order of 20.3 and 29.2 pC/N, respectively, with the electromechanical coupling coefficients being k33 = 36.6% and k15 = 14.3%. Moreover, temperature dependence of the electro-elastic coefficients was measured in the range of 0–150 °C, where the elastic constant s44 was found to possess relatively low temperature coefficient (Ts44(1) = 77 × 10−6/ °C), and the variations of d33 and k33 were less than 3.5% and 1.0%, respectively.

Bulk growth, structure, and characterization of the new monoclinic TbCa4O(BO3)3 crystal

Bulk TbCa4O(BO3)3 single crystals with diameter of 25 mm and length of 70 mm were successfully grown by the Czochralski (Cz) method for the first time to the best of our knowledge. The main problems of crystal growth were discussed and solved resulting in a high quality crystal. The crystalline perfection of the as-grown crystal was evaluated with full-width at half-maximum (FWHM) of the rocking curve being 35.05′′, and the optical homogeneity being 7.76 × 10−5. TbCa4O(BO3)3 crystallizes in the monoclinic space group Cm with unit cell parameters of a = 8.0715(7) A, b = 16.0000(15) A, c = 3.5454(3) A, and β = 101.2550(10)°. Several interesting phenomena of atom occupancy and structure distortion were observed and analysed. Furthermore, the hardness, density, absorption and transmission spectra were measured. The TbCOB crystal has a Mohs hardness value of 5.58, and it exhibits a high transparency ranging from 490 nm to 1500 nm.

Investigation of the second-order nonlinear optical properties of Cs2TeMo3O12 single crystal

The complete set of second-order nonlinear optical (NLO) coefficients of Cs2TeMo3O12 single crystals were obtained using the Maker Fringe techniques. The NLO coefficients d32 and d33 were measured to be on the order of 6.8 and 6.5 pm/V, respectively. Irradiated by 1064 nm laser, the crystal is phase-matchable, and its effective nonlinear coefficient is 4.6 pm/V for type I phase matching at θ = 42.7°. The relationship between the second-order nonlinear properties and the crystal structure is also discussed. Considering its wide transmission range, phase matching, and large effective NLO coefficient, Cs2TeMo3O12 is a good candidate for IR NLO application.

Bulk crystal growth and characterization of semi-organic nonlinear optical crystal tri-diethylammonium hexachlorobismuthate (TDCB)

Bulk semi-organic nonlinear optical (NLO) single-crystals of tri-diethylammonium hexachlorobismuthate (TDCB) with sizes up to 22 × 21 × 15 mm3 have been grown from concentrated hydrochloric acid by the slow-cooling method. TDCB crystallizes in the trigonal system, the R3c space group, with a = 14.699(4) A and c = 19.102(5) A. Its morphology has been indexed to reveal the major facets of the crystal to be {110} and {012}. Transmittance spectra of TDCB show an optical transmission in the entire visible region with the cutoff wavelength at 365 nm. The powder second harmonic generation (SHG) measured by using the Kurtz and Perry technique indicates that TDCB is a phase-matchable NLO material with a SHG efficiency of 1.8 times that of KH2PO4 (KDP). Its specific heat and thermal expansion were investigated as a function of temperature, and the relationship between the structure and the thermal properties has been discussed. Furthermore, laser-induced damage threshold measurements show a threshold up to 2.32 GW cm−2. All the results demonstrate that the semi-organic crystal TDCB is promising in NLO applications.

Growth and electric-elastic properties of KTiOAsO4 single crystal

We report the successful growth of high quality potassium titanyl arsenate, KTiOAsO4 (KTA) crystals with size of 34×67×72 mm3 through a K6As4O13 based flux method. The dielectric, piezoelectric, and elastic constants of KTA crystal were determined by the resonance technique and impedance analysis, respectively. The thermal dependence of the elastic constants were also determined by the transmission method over −50–110 °C. The first, second, and third order temperature coefficients of the elastic constants were calculated (T0=25 °C).

Temperature dependence of elastic properties and piezoelectric applications of BaTeMo2o9 single crystal [Correspondence]

BaTeMo2O9 (BTM) single crystal, as a lead-free piezoelectric material, belongs to the monoclinic system, space group P21. We report the temperature dependence of the elastic constants by the transmission method over the range -50°C to 150°C. The first-order temperature coefficients of the elastic constant s44 is about 180 × 10-6/°C. Piezoelectric resonators based on BTM crystal using the thickness-stretching vibration and the shear vibration modes were designed and evaluated, which eliminated or minimized the influence of the off-principal axis coefficients. The Qm of one of the resonators is about 600. Our results show that the elastic constants have good temperature stability, and the resonators have already met the requirements for some piezoelectric applications. This study on the BTM crystal has revealed the application for the low-symmetry crystal.

Self-frequency-doubled BaTeMo 2 O 9 Raman laser emitting at 589 nm

In this paper, the spontaneous Raman spectra and second harmonic generation (SHG) properties at 589 nm of a novel Raman crystal BaTeMo(2)O(9) (BTM) were investigated. The BTM crystal was cut along the type-II SHG phase-matching direction for the first-order Raman shift at 1178 nm to realize the SRS and SHG simultaneously. Pumped by a nanosecond 1064 nm laser source, a self-frequency-doubled BTM Raman laser operating at 589 nm has been demonstrated for the first time. At the pump pulse energy of 48 mJ, the maximum yellow laser output pulse energy of 5.6 mJ was obtained with an optical-to-optical conversion efficiency of 11.7%. Our results show that BTM crystal is one of the promising candidate Raman materials to generate yellow laser radiation.