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A good quality single crystal of Tm3+ doped YPO4 crystal was grown utilizing the flux method using a lead or molybdenum free flux. The spectroscopic properties of the crystal were investigated. The absorption cross-section of Tm3+:YPO4 at 791 nm is as large as 3.09 × 10−20 cm2. The intensity parameters Ω2,4,6, radiative transition rates, branching ratios and radiative lifetime were calculated by using the Judd–Ofelt theory. The strong experimental emission cross-section has an astounding value of 6.71 × 10−20 cm2 and is located at 1802 nm. All the results indicate that the Tm3+:YPO4 crystal is a potential laser medium crystal. [ABSTRACT FROM AUTHOR]

A new Sm-doped calcium oxyborate crystal, SmxGd1−xCa4O(BO3)3 (Sm:GdCOB), was grown by the Czochralski (Cz) method. The cell parameters were determined to be a = 8.0910 Å, b = 16.0090 Å, c = 3.5571 Å, β = 101.267°, and Z = 2 with the Cm space group. The density was determined to be 3.72 g cm−3 by the Archimedes method. The thermal properties, including thermal expansion coefficient, the thermogravimetric and differential thermal analysis (TG-DTA) as well as specific heat were investigated systematically. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay lifetimes of the Sm:GdCOB crystal were measured at room temperature. Based on the J–O theory, various spectra parameters, such as polarized absorption cross-section, intensity parameters, transition probabilities, radiative lifetime, and branching ratios were obtained, and the polarized stimulated emission cross-sections were determined. For the Sm:GdCOB crystal, excellent physical properties, such as rapid growth with large size, high specific heat (0.585 J g−1 K−1, RT), large quantum yield (76%), and strong emission around 600 nm predict potential application as a reddish-orange laser medium. In addition, the Sm:GdCOB crystal exhibits a distinct saturable absorption characteristic at 1064 nm, indicating that it can be used as a pulse modulation material in the solid-state laser. [ABSTRACT FROM AUTHOR]

Large size HoCa4O(BO3)3 (HoCOB) crystal was successfully grown by the Czochralski (Cz) method. Through single-crystal X-ray diffraction the cell parameters were determined to be a = 8.090(3) Å, b = 16.018(7) Å, c = 3.5317(14) Å, β = 101.28°(4) and Z = 2 with the space group Cm. The Archimedes method was used to measure the density which was 3.85 g cm−3. In the transmittance spectrum of HoCOB, there are strong absorption peaks from 200 to 680 nm and 1800 to 2200 nm, corresponding to the Stokes levels between 13 219 and 49 335 cm−1. The thermal and the piezoelectric properties were investigated under different temperatures. At 300 K around, the thermal expansion coefficient, thermal conductivity, specific heat, and relative dielectric constant on the b axis direction (i.e. the unique two-fold axis direction) were 5.35 × 10−6 K−1, 2.18 W m−1 K−1, 0.58 g−1 K−1, and 12.5, respectively. [ABSTRACT FROM AUTHOR]

Disordered crystals have garnered increasing attention as new laser materials because of their broad emission bandwidths. This paper reports a novel Yb-doped strontium yttrium phosphate (Yb:YSr3(PO4)3) crystal with a disordered structure, as well as its crystal growth, structure, spectral properties, and laser performance. The crystal structure (cubic, 4¯3m point group) was refined using the Rietveld method. The absorption cross-section and fluorescence lifetime were determined to be 1.31 × 10−20 cm2 at 976 nm and 1267 μs, respectively. The stimulated emission cross-section was 1.04 × 10−20 cm2 at 1013 nm, with an emission bandwidth of 55 nm. In addition, continuous-wave laser operation was realized using the Yb:YSr3(PO4)3 crystal with different output coupler transmissions, where the obtained maximum output power and slope efficiency were 1.3 W and 61%, respectively. A dual-wavelength regime with wavelengths centered at 1039 nm and 1047 nm (Δν = 2.2 THz) was achieved under certain conditions; thus, this crystal is expected to be employed for developing terahertz sources. In addition, the laser can operate at multiple wavelengths, ranging from 1023 to 1050 nm. The results indicate that the Yb:YSr3(PO4)3 crystal with a disordered structure may be a promising multi-wavelength laser crystal. [ABSTRACT FROM AUTHOR]