Ch. Y. Gao

Thermal properties of calcium doped strontium barium niobate crystal

Calcium doped strontium barium niobate is a tungsten-bronze ferroelectric crystal with a tetragonal unit cell. Thermophysical properties including specific heat, thermal expansion, and thermal diffusion were performed on a single crystal (Ca0.28Ba0.75)0.25(Sr0.60Ba0.40)0.75Nb2O6 (CSBN25) to determine thermal behaviors along the a and c axes. Negative thermal expansion was observed along the c axes below the Curie temperature. Isotropic thermal behavior (thermal diffusion and thermal conductivity) was observed around Curie temperature. The abnormal thermal behaviors are considered as arising due to the geometry of the dope-affected crystal.

Lattice vibration and thermal diffusion of Yb doped KLu(WO4)2 single crystal

Yb doped KLu(WO4)2 (Yb:KLuW) single crystal was grown by the method of top-seeded-solution growth slow-cooling method. Its lattice vibrational modes were calculated by using space group theory, and polarized Raman spectra were measured at room temperature with different scattering geometry projections. The powder transmission of Fourier-transform infrared spectra was also performed as a supplement for Raman spectra to study the lattice vibration of the laser crystal. The main Raman peaks and infrared transmission bands were attributed to the internal mode WO6 octahedrons in the crystals. Two kinds of link ways of WO6 octahedrons implying large distortion had led the Raman peaks to shift to different positions. Large distortions of the WO6 octahedrons in the crystal had led to the splitting of some Raman peaks and even the activation of ν6 mode, which is originally a silent mode by the selection rule. As a self-Raman crystal, the linewidth of the Raman peaks ν1 and ν2 reached 12.5 and 16.6cm−1, with relaxa...

Shifting bright spatial solitons in LiNbO 3

We observe spatial bright solitons in a transversely shifting LiNbO3 crystal. In this scheme, the photovoltaic nonlinearity in LiNbO3 can be switched from self-defocusing to self-focusing by continuous shifting of the beam. Moreover, the shifting velocity has a strong influence on the wave shape of the bright spatial solitons.

Passively Q-switched mode-locking in a diode-pumped Nd:LuVO4 laser with V:YAG

A passively Q-switched and mode-locked Nd:LuVO4 laser with V:YAG at 1.34 μm was successfully demonstrated. Comparisons between c-cut and a-cut Nd:LuVO4 lasers were experimentally made. The maximum average output power of 170 mW, the highest Q-switched pulse energy of 4.5 μJ were obtained in c-cut Nd:LuVO4 laser. The duration of mode-locked pulse was estimated to be less than 540 ps with repetition rate of 110 MHz.

Evolution of bright spatial solitons in a transversely shifted photorefractive crystal

The dynamic evolution of bright spatial solitons induced by the transverse shifting of the beam is investigated. Transverse shifting can result in the formation and dynamic evolution of bright spatial solitons in photorefractive materials. To explain the phenomena, a uniform theoretical physical model is proposed. Numerical analysis results show that the beam shifting has strong influence on the formation and dynamic evolution of bright spatial solitons.

Photorefractive dynamic properties of Ca 2+ -doped strontium barium niobate crystals

Measurements for photorefractive dynamic properties under polarized light with different luminous intensity and wavelength at 650 nm were performed in calcium-doped strontium barium niobate crystals as a function of the time. Experimental results further validated that the different input luminous intensities influence only the saturated time and photorefractive velocity of the photorefractive crystals. Birefringence experiments suggest that an input luminous intensity oscillatory threshold should exist between 64 mW/cm(2) and 13 mW/cm(2). The dynamic change of refractive index from self-focusing to asymmetric self-defocusing was also measured and regarded as the mutual results of the nonuniform-intensity incidence and positive thermal lens effect, which was validated by a further experiment based on the Michelson interference. Also, oscillation accompanying change in the dynamic indices was analyzed and attributed to the high dielectric effect as well as asymmetric self-defocusing in this investigation.