Han Jianru

Studies on the growth and defects of GdCa4O(BO3)3 crystals

Abstract New nonlinear optical crystals GdCa4O(BO3)3 grown by the Czochralski method in a platinum crucible under air atmosphere are reported in this paper. The growth mechanism is a typical two-dimensional nucleation layer growth. The twin and inclusion defects of this crystal are observed using optical microscopy. The incidence of twinning is in good agreement with Hurles model. The approaches to reduce and eliminate the defects are presented.

The piezoelectric and elastic properties of berlinite and the effect of defects on the physical properties

Abstract Single crystals of berlinite (α-AlPO 4 ) have been grown by the slow heating method in an autoclave. The piezoelectric and elastic constants have been measured by the transmission method at 25°C. In addition, the influences of various defects in the crystals on the electric properties were studied.

Growth and Second-Harmonic Generation Properties of Tm3+, Yb3+, Bi3+ and Li+ Doped GdCa4O(BO3)3 Crystals

The rare-earth ions (Yb3+, Tm3+) and Li+, Bi3+ ions doped GdCa4O(BO3)3 crystals were grown using the Czochralski pulling method. The second-harmonic generation conversion efficiencies of the GdCOB:Yb and GdCOB:Tm crystals are 31.3% and 33.3%, respectively, while the undoped GdCOB crystal is 27.9%. The conversion efficiencies of Yb3+, Tm3+ doped GdCOB are improved by 12% and 19%, respectively, compared to that of the undoped one. The conversion efficiencies of Li+, Bi3+ doped GdCOB crystals are 33% and 38.3%, which are improved by 15% and 37% as compared to that of the undoped crystal. The results are discussed using the anion group theory.

Effect of Strontium Ion on the Growth and Second-Harmonic Generation Properties of GdCa4O(BO3)3 Crystal

Large sized and optical quality GdCa4O(BO3)3 (GdCOB) crystal with calcium partially substituted by strontium (Sr) ions was grown for the first time. The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal. Second-harmonic generation (SHG) experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction. The results show that the cw green laser output power is 1.04 W when the laser diode pump power is 10 W in the Nd:YVO4/Sr:GdCOB intracavity laser. Considering the slope efficiency of Nd:YVO4 and the fundamental laser in cavity, the intracavity SHG conversion efficiency of the GdCOB crystal is 21% while it is 24% for the Sr:GdCOB crystal, the SHG conversion efficiency is improved by 14%. The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory. PACS: 42. 65. Ky, 78. 20. -e, 78. 55. Hx

Studies on Lead Tungstate Crystal

The growth of lead tungstate (PWO) single crystals and their luminescence properties such as light yield, scintillation decay time, and transmittance were reported. The colourless PWO single crystal has been obtained by using the presyntheses powder. Ba, Nb, and Mg ions were doped in the crystals and the Ba-doped crystal has a relatively short decay time. Annealed crystal was found having a better transmission spectrum than that of unannealed one.

LOW TEMPERATURE PHASE TRANSITION OF A CRYSTAL IN THE POTASSIUM LITHIUM NIOBATE SYSTEM

A potassium lithium niobate crystal with tetragonal tungsten bronze structure was prepared by the Czochralski technique. The dielectric and pyroelectric properties were investigated in the temperature range of 300 to 10 K. A broadened ferroelectric-ferroelectric transition between phases with space group 4mm and space group m was found at about 80K.