M.H. Jiang

Synthesis, structure and properties of a new nonlinear optical material: zinc cadmium tetrathiocyanate

In this communication, a new nonlinear optical crystal of coordination complex, zinc cadmium tetrathiocyanate (ZnCd(SCN)4), is reported. It was successfully synthesized through several reactions in water. For the crystal structure, optical and thermal characterization were determined by elemental analysis, X-ray diffraction, infrared spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and transmission spectrum. It belongs to the tetragonal system, space group I4, with a = 11.135(2), c = 4.3760(10) A, and z = 2. It exhibits powder SHG efficiencies superior to that of cadmium mercury thiocyanate (CMTC) and over 10 times that of urea, and the UV transparency cutoff is 290 nm, which is shifted to violet band 90 nm, compared with that of CMTC.

Laser self‐doubling in neodymium yttrium aluminum borate

The nonlinear effects of neodymium yttrium aluminum borate NdxY1−xAl3(BO3)4 (NYAB) crystal powder samples with different Nd3+ mole percentage are reported in this paper. The optimum X value for the growth of NYAB crystals with high optical homogeneity has been determined. The performance of laser self‐frequency doubling from 1.06–0.53 μm has been realized, for the first time, in a 5×3×3 mm3 NYAB crystal. The Nd3+ ions in crystal show weak absorption at 0.53 μm. The threshold energy is measured to be less than 2 mJ; the output energy of green light at 0.53 μm is more than 5 mJ and the conversion efficiency is over 10%. The experiments show that the performance is improved if the optical path length is increased and the cavity design is improved. The refractive indices n0 and ne of the crystal have been measured by the prism method at different wavelengths. The phase‐matching angles of Types I and II have been obtained by solving equations for the phase‐matching angles. The results are in good agreement wit...

Efficient diode-pumped actively Q-switched Nd:YAG/BaWO~4 intracavity Raman laser

Barium tungstate (BaWO4) is employed to achieve efficient stimulated Raman scattering conversion in a compact diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 9.2 W, 1.56 W of 1181 nm first-Stokes average output power was generated at a pulse repetition rate of 20 kHz, corresponding to an optical-to-optical conversion efficiency of 16.9%.

The preparation and characterization of a new organometallic nonlinear optical material — Tri-allylthiourea mercury bromide (ATMB) crystal

Abstract This paper describes the growth of an organometallic nonlinear optical material tri-allylthiourea mercury bromide grown from aqueous solution by temperature-lowering method. Its powder SHG intensity is 3.5 times as high as that of urea. The dimension of ATMB crystal can reach 13×13×10 mm 3 . The as-grown crystals have been characterized and its linear optical properties are also presented.

Synthesis, growth, and characterization of Nd-doped SrGdGa3O7 crystal

A disordered Nd:SrGdGa3O7 (Nd:SGGM) laser crystal was grown by the Czochralski method. The space group and effective segregation coefficient of Nd3+ were determined to be P4¯21m and 1.36, respectively. Thermal properties, including the average linear thermal expansion coefficient, thermal diffusivity, specific heat, and thermal conductivity were measured. It was found that the thermal conductivity increases with increasing temperature, indicating glasslike behavior. Sellmeier’s equations were fitted by measuring the refractive indices in the range of 253–2325 nm. The polarization absorption and emission spectra were measured at room temperature, and Judd–Ofelt analysis was carried out to calculate the fluorescence branching ratios from the upper F43/2 state and the fluorescence lifetime. The stimulated emission cross section for the F43/2→I411/2 transition was calculated to be 2.00×10−20u2002cm2. Finally, a diode-pumped laser experiment at 1.06u2002μm is described. Thermal, optical, and laser properties have show...

Thermal and mechanical properties of BaWO4 crystal

A large single crystal of barium tungstate (BaWO4) with dimensions of 22-mmdiameter×80-mm length was grown by the Czochralski method using an iridium crucible. The melting point, molar enthalpy of fusion, and molar entropy of fusion of the crystal were determined to be 1775.10 K, 96913.80Jmol−1, and 54.60JK−1mol−1, respectively. The average linear thermal-expansion coefficients are αa=10.9526×10−6∕K, αb=10.8069×10−6∕K, and αc=35.1063×10−6∕K in the temperature range from 303.15 to 1423.15 K along the three respective crystallographic axes. The density of the crystal follows an almost linear decrease from 6.393×103 to 6.000×103kgm−3 when the temperature is increased from 303.15 to 1423.15 K. The measured specific heat are 115.56–130.96JK−1mol−1 in the temperature range of 323.15–1173.15 K. The thermal diffusion coefficient of the crystal was measured in the temperature range of 297.15–563.15 K. The calculated thermal conductivity is 2.256Wm−1K−1 along the [001] direction and 2.324Wm−1K−1 along the [100] dir...

Efficient diode-pumped actively Q-switched Nd : YAG/BaWO4 intracavity Raman laser

Barium tungstate (BaWO4) is employed to achieve efficient stimulated Raman scattering conversion in a compact diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 9.2 W, 1.56 W of 1181 nm first-Stokes average output power was generated at a pulse repetition rate of 20 kHz, corresponding to an optical-to-optical conversion efficiency of 16.9%.

Characterization of mixed Nd:LuxGd1−xVO4 laser crystals

A series of laser crystals Nd:LuxGd1−xVO4 (x=0.14,0.32,0.50,0.61,0.70,0.80) was grown by the Czochralski method. The thermal properties, including the average linear thermal expansion coefficients, thermal diffusion coefficients, specific heats, and thermal conductivities, of the mixed crystals were obtained. The material constants Ms for the thermal stress resistance figure were calculated and showed that the thermal fracture limits of the mixed crystals should be comparable with that of Nd:YVO4. The polarization absorption spectra from 240to1000nm were measured at room temperature and the absorption cross sections at 809nm were calculated. Using the Judd-Ofelt theory, the theoretical radiative lifetimes were calculated and compared with the experimental results. Continuous wave laser performances were achieved with the mixed crystals at the wavelength of 1.06μm when they were pumped by a laser diode. Thermal, optical, and laser properties have shown variation as a function of x and proved that the mixed...

Growth and thermal properties of SrWO4 single crystal

A strontium tungstate (SrWO4) single crystal with dimensions of Φ 25×40mm2 has been grown by the Czochralski method using an iridium crucible. X-ray powder diffraction results show that as grown the SrWO4 crystal belongs to the tetragonal system in the scheelite structure. The effective segregation coefficients of elemental W and Sr in the crystal growth are measured by x-ray fluorescence, and the respective values are close to 1. The thermal properties of the SrWO4 crystal were systemically studied by measuring the thermal expansion, specific heat, and thermal diffusion coefficient. These results show that the crystal possesses a large anisotropic thermal expansion with thermal-expansion coefficients αa=8.61×10−6∕K, αb=8.74×10−6∕K, αc=18.78×10−6∕K over the temperature range of 303.15–773.15K. The measured value of the specific heat is 0.30–0.34Jg−1K−1 when the temperature is increased from 323.15to1073.15K. The thermal diffusion coefficient was measured over the temperature range of 303.15–543.15K. The t...

Low temperature benzene thermal synthesis and characterization of boron nitride nanocrystals

Abstract Hexagonal boron nitride nanocrystals were synthesized by reacting Li 3 N and BBr 3 at low temperature benzene thermal conditions and they are characterized by XRD, IR, TEM and XPS. The results show that when the temperature is low, hexagonal BN nanocrystals can be obtained which are uniform in granularity and regular shape. However, benzene molecules dissociated on the surface of BN nanocrystals at higher temperature, and that it is difficult to obtain BN samples with higher purity. In addition, thermal analysis of hexagonal BN nanocrystals shows that when the average size reduced to about 1.0 nm, its melting point decreases from 2967°C of the bulk BN to about 1240°C.