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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]

A novel Tm3+-doped YSr 3 (PO 4) 3 (Tm:YSP) crystal with a disordered crystal structure was grown by using the Czochralski pulling method. The single crystal growth, structure, absorption and emission spectra were systematically analyzed. The absorption bandwidth at ∼792 nm was found to be 21 nm, showing that the Tm:YSP crystal was very suitable for commercial laser diodes pumping of AlGaAs. Furthermore, the maximum emission cross section centering at 1835 nm was determined to be 0.86 × 10−20 cm2 with an emission bandwidth of 202 nm, which indicates the promising applications in the fields of ultrafast and tunable lasers. In addition, Spectroscopic parameters, containing Judd – Ofelt intensity, line strengths, radiative transition probabilities, fluorescence branching ratio and radiative lifetime, were analyzed by using the Judd – Ofelt theory. All above results showed that the Tm:YSP crystal with a disordered structure was a potential laser medium in the ⁓ 2 μm region. • A novel disordered crystal Tm:YSr 3 (PO 4) 3 was grown by the Czochralski method. • Spectroscopic property of the Tm:YSr 3 (PO 4) 3 crystal was investigated. • A broad emission bandwidth at around 2 μm was observed in this crystal. [ABSTRACT FROM AUTHOR]

A bulk Nd:LaCa 4 O(BO 3) 3 (Nd:LaCOB) single crystal with the low Nd3+-doping concentration (~0.5 at%) was grown by Czochralski (Cz) method. Its powder X-ray diffraction, Nd3+ ions doping concentration, polarized transmittance and emission spectra, and fluorescence lifetimes were tested. Based on the Judd-Ofelt theory, the spectral parameters of Nd:LaCOB (Nd3+, ~0.5 at%) crystals including polarized absorption and emission cross sections, spontaneous transition probability, fluorescence branching ratio, theoretical fluorescence lifetime and intensity parameters (Ω 2 , Ω 4 and Ω 6) were systemically investigated. The calculated radiation lifetimes were compared with the experimental values, resulting in a quantum yield of 33%, which was the highest record among all the Nd:ReCOB (Re: Y, Gd, La 1−x Gd x) type crystals. The spectral properties of Nd:LaCOB were found to be better than those of Nd:YCOB and Nd:GdCOB crystals, especially in polarized absorption and emission cross sections. The self-frequency-doubling (SFD) angles were calculated according to the main fluorescence peaks of Nd:LaCOB (Nd3+, ~0.5 at%) crystals such as 1041 nm, 1060 nm, 1090 nm and 1102 nm, which would be excited and frequency doubled into blue-green, green, yellow-green and yellow lasers. All the results showed that the Nd:LaCOB crystals had potential applications in the field of laser and SFD. [ABSTRACT FROM AUTHOR]

• A bulk crystal of Nd3+:YBa 3 (PO 4) 3 (Nd:YBP) was successfully grown by the Czochralski method. • The thermal properties and Judd – Ofelt analysis of Nd:YBP crystal. • The absorption and fluorescence spectra were investigated in detail. • A diode-pumped continuous-wave laser was firstly realized in Nd:YBP crystal. A novel laser crystal Nd3+-doped yttrium barium phosphate (Nd:YBa 3 (PO 4) 3 , hereafter Nd:YBP) with disordered crystal structure was reported. Single crystal growth, thermal, spectral and laser performances were investigated. The thermal conductivity at room temperature was found to be 1.35 W·m−1·K−1 and shown an increased tendency with increased temperature. The spontaneous transition probabilities, radiation lifetime and other parameters were evaluated by using the Judd-Ofelt (J-O) theory. The maximum absorption and emission cross sections for Nd:YBP crystal were obtained to be ∼ 2.32 × 10−20 cm2 (@ 804 nm) and 6.72 × 10−20 cm2 (@ 1056 nm), respectively. The measured fluorescence lifetime for Nd:YBP crystal was equal to 351 μs. Furthermore, diode-pumped continuous-wave laser operation was firstly realized near 1060 nm. The slope efficiency was found to be approximately 22% and the maximum output power for Nd:YBP crystal was 256 mW. Results reveal that the disordered crystal Nd:YBP might be further optimized for uses in laser field. [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]