Luo Haosu

Growth units model of anion coordination-polyhedra and its application to crystal growth

Growth units model of anion coordination-polyhedra ACP model emphasizes the influence of intrinsic structure of crstal upon the crystal growth and the importance of the external conditions on which crystals grow. The ACP model is used to analyze some problems in crystal growth, such as the formation of dendrite in the crystal structure, growth habit of polar crystal, and formation of allomerism and polymorphism.

Optical Dispersion Behavior and Band Gap Energy of Relaxor Ferroelectric 0.92Pb(Mg1/3Nb2/3)O3-0.08PbTiO3 Single Crystal

Refractive indices and extinction coefficients of 0.92Pb(Mg1/3Nb2/3)O3-0.08PbTiO3 (PMN-0.08PT) single crystal are investigated by variable angle spectroscopic ellipsometry (VASE) at different wavelengths. The parameters relative to the energy band structure are obtained by fitting to the single-oscillator dispersion equation, and the band gap energy is also deduced from the Tauc equation. Similar to most oxygen-octahedra ferroelectrics, PMN-0.08PT has the same dispersion behavior described by the refractive-index dispersion parameters.

Noise Reduction in Photorefractive Image Amplification by Contradirectional Two-Wave Mixing in Rh-Doped BaTiO3 Crystal

Low noise image amplification owing to contradirectional two-wave mixing (CTWM) is proposed and demonstrated in Rh-doped BaTiO3 crystal. Comparing with the conventional forward two-wave mixing scheme, an enhancement of signal-to-noise ratio in the order of 103 is obtained. The theoretical analyses are presented and give a reasonable explanation for the experimental results. The further discussion shows that CTWM scheme can also reduce the influence of the crystal absorption and crystal size on the two-wave mixing process to rise the signal beam gain.