Shiyi Guo

Crystal growth and physical properties of UV nonlinear optical crystal zinc cadmium thiocyanate, ZnCd(SCN)4

Abstract Zinc cadmium thiocyanate, ZnCd(SCN) 4 (ZCTC) single crystals of optical quality have been grown from aqueous solution by controlled evaporation at 40 °C. The morphology of the crystal was indexed. Raman spectroscopy, refractive indices, optical transmission and optical damage threshold of the ZCTC crystal were all performed at room temperature. Violet and ultraviolet (UV) light output by frequency doubling of a 808 nm GaAlAs laser diode and a continuous wave Ti:sapphire laser at 760 nm were achieved. The dielectric constants, piezoelectric strain constants, electroptic coefficients, and direct current resistivities have also been measured.

Growth and properties of UV nonlinear optical crystal ZnCd(SCN)4

Abstract A second-order nonlinear optical coordination crystal, zinc cadmium thiocyanate, ZnCd(SCN) 4 (ZCTC) was grown as a frequency doubler, emitting UV light. A large typical single crystal with dimensions up to 15 × 7 × 7 mm 3 has been obtained by slow solvent-evaporation method for the first time. The infrared (IR) spectroscopy and X-ray powder diffraction (XRPD) of single crystals were performed at room temperature. The specific heat of the crystal has been measured to be 367.9 J/mol.K at 300 K. The thermal expansion coefficients, c- and a-oriented, have been measured to be −1.69 × 10 −5 and 1.95 × 10 −4 K −1 , respectively. The second harmonic generation (SHG) efficiency of ZCTC crystal is 51.6 times as high as that of urea reference, and the measured transmittance spectra from 190 to 3200 nm showed that the UV transparency cutoff occurs at 290 nm and the transmission is 73.22% at 380 nm. UV laser light of wavelength 380 nm has been achieved by the frequency doubling of a 760 nm laser diode at room temperature.

Investigation of the dielectric and piezoelectric properties of ReCa4O(BO3)3 crystals

Piezoelectric ReCa4O(BO3)3 (ReCOB, Re: rare earth) crystals, including ErCOB, SmCOB, PrCOB and LaCOB, were successfully grown by the Czochralski (Cz) method. The dielectric constants were determined to be , and for ErCOB, , and for SmCOB, , and for PrCOB, , and for LaCOB, respectively. The electromechanical coupling factors k26 and piezoelectric coefficients d26 were found to be 18.5% (7.6 pC N−1), 27.0% (12.7 pC N−1), 31.5% (15.8 pC N−1) and 25.0% (11.8 pC N−1) for ErCOB, SmCOB, PrCOB and LaCOB crystals, respectively. The dielectric and piezoelectric properties as a function of Re3+ ion radius were studied, with maximum values being observed in the PrCOB crystals, due to the similar ion radius of Pr3+ and Ca2+. The relationship between the structure and dielectric/piezoelectric properties of ReCOB crystals was explored, to further optimize the dielectric and piezoelectric properties in ReCOB series crystals.

Crystal growth and characterization of a new organometallic nonlinear-optical crystal material: MnHg(SCN)4(C3H8O2)

A potentially useful second harmonic generation (SHG) organometallic nonlinear-optical crystal: manganese mercury tetrathiocyanate glycol monomethyl ether, MnHg(SCN) 4 (C 3 H 8 O 2 ) (MMTG) has been prepared, and high optical quality single crystals have been successfully grown by the slow temperature-lowering technique. Its structural, physicochemical and optical properties are characterized by elemental analyses, infrared spectroscopy, transmission electron microscopy (TEM), X-ray powder diffraction, thermal analysis, powder SHG measurements and Vis/UV/NIR spectroscopy. The results of characterizations have shown that MMTG possesses good physicochemical stabilities up to 145 °C, exhibits powder SHG efficiencies close to that of urea. The UV transparency cutoff is 375 nm, and the transmission is 33.54% at 404 nm, the sample thickness was 2.76 mm, which is 6% greater than that of MnHg(SCN) 4 (MMTC).

Crystal growth and characterization of Sr3TaGa3Si2O14 single crystals

High quality piezoelectric single crystals Sr3TaGa3Si2O14 were grown using the conventional Czochralski method along the Y-axis. The mass density was found to be 5.121?g?cm?3 by the Archimedes method. The relative dielectric constants, piezoelectric strain coefficients and elastic compliance constants of Sr3TaGa3Si2O14 single crystals were determined by an electric bridge and the resonant?antiresonant method at room temperature. The results were , , d11 = ?4.90?pC?N?1, d14 = 3.20?pC?N?1; ; ; ; ; ; and , respectively. The temperature dependent behaviour of elastic compliance constants was also investigated, where zero temperature compensated cuts were not found in the range from ?40 to 120??C.

Crystal growth, experimental and theoretical studies on the electronic structure of CNGS and Nd:CNGS

Ca3NbGa3Si2O14 (CNGS) and Nd:Ca3NbGa3Si2O14 (Nd:CNGS) single crystals were grown using the Czochralski technique, and the dielectric, elastic and piezoelectric properties of the Nd:CNGS crystals were evaluated at room temperature by the impedance method. It is proved that the Nd:CNGS crystals have larger dielectric constants, piezoelectric constants and elastic compliance as compared with the CNGS crystals. The electronic structure and chemical composition of the crystals were analyzed using X-ray photoelectron spectroscopy (XPS). Constituent element representative core levels and auger lines in this complex langasite crystal have been measured. The Ca 2p, Ca 3p, Ga 3p, Ga 3d, Si 2p XPS spectra show a shift toward higher binding energies while the O 1s level moves in the lower binding energy direction with increasing Nd content and can be interpreted as a doping induced change in the chemical potential. Furthermore, it was confirmed by the X-ray photoelectron spectra that Ca–O, Ga–O, and Si–O bonds in Nd:CNGS have stronger ionicity compared with the CNGS crystal. On the basis of the density functional theory (DFT), first-principles calculations have been employed to study the electronic structure of CNGS successfully. The calculated results are essentially consistent with the corresponding experimental results, which indicate that the contributions of the Nb–O groups are dominant in the CNGS crystal for producing optical properties.

Growth and optical properties of a new CGG-type laser crystal Nd 3+ :CNGS

A novel CGG-type laser crystal of Nd3+:CNGS is characterized, including crystal growth, structure, refractive index, spectroscopic and laser performance. For Nd3+:CNGS crystal, the unit-cell parameters are a = 0.88897 ( ± 8.89 × 10−5) nm, c = 0.497998 ( ± 4.85 × 10−5) nm and V = 0.28219 nm3. The refractive index no and ne of Nd3+:CNGS were calculated to be 1.772 and 1.854 respectively at 1065 nm. The transmittance spectra of Nd3+:CNGS were measured, four main absorption peaks were located at 586 nm, 748 nm, 804 nm and 804 nm respectively. The absorption cross-section in z-axis is 6.08 × 10−20 cm2 around 804nm. The strongest emission peak of the fluorescence spectra was located at 1064 nm with the emission cross-section of 6.81 × 10−20 cm2 for E//x polarization and the fluorescence lifetime was 255.6 μs. Moreover, the continuous-wave laser at 1065 nm was obtained with the maximum output power of 1.43 W in the z-cut sample for the first time to the best of our knowledge, the optical conversion efficiency was 29.3% and the slope efficiency was 31.0%, which indicated that Nd3+:CNGS crystal should be a promising gain material.

Crystal growth and characterization of La3Ga5SiO14 single crystals

Abstract An almost colorless La3Ga5SiO14 (LGS) single crystal with 26 mm in diameter and 25 mm in length was grown by the Czochralski technique. The coloration of the crystal depends on the growth atmosphere. The cutoff wavelength of the colorless LGS crystal is shorter than an annealed crystal and the piezoelectric properties of the former are nearly equal to those of the colored one.

Growth, thermal and laser properties of a new self-frequency-doubling Yb:CNGS crystal

A new optical single-crystal Yb:CNGS (Yb:Ca3NbGa3Si2O14) was grown successfully for self-frequency-doubling with the sizes of 25 mm in diameter and 50 mm in length using the Czochralski methods. We studied the thermal properties of these crystals systematically, including the thermal expansion coefficient, specific heat, thermal diffusion coefficient, and the thermal conductivity. The absorption and fluorescence spectra of Yb:CNGS crystal were measured. The absorption spectra show a broad transmission range from 350 to 3500 nm. The continuous-wave (CW) laser output at 1060 nm was demonstrated with a- and c-cut crystal. The maximum output power was about 1.53 W under a 4.03 W incident power with z-cut crystals. The slope efficiency was as high as 47.8%. An efficient CW self-frequency-doubling (SFD) green laser was performed with a diode-pumped Yb:CNGS laser. The CW green output power was 37.1 mW and the wavelength tunability from 526 to 532 nm with input pump power as been demonstrated.

Preparation and transmission loss of the nano-crystal and polymer composite film BTO/PMMA

Abstract Bismuth titanate, Bi 4 Ti 3 O 12 (BTO), is a typical ferroelectric material with useful properties for optical memory, piezoelectric and electro-optic devices. Its nano-crystals were compounded by the chemical solution decomposition technique. The structure and size of BTO were analyzed by X-ray diffraction and transmissive electron microscopy. Two sorts of composite films BTO/polymethylmethacrylate with different weight ratio of BTO were prepared by spin-coating method at certain conditions. In this article, the scattering loss in thin films was obtained using an imaging technique.