Z. B. Lin

Five new chalcohalides, Ba3GaS4X (X = Cl, Br), Ba3MSe4Cl (M = Ga, In), and Ba7In2Se6F8: syntheses, crystal structures, and optical properties.

Five new chalcohalides, Ba3GaS4X (X = Cl, Br), Ba3MSe4Cl (M = Ga, In), and Ba7In2Se6F8, have been synthesized by conventional high-temperature solid-state method. These compounds crystallize in three different interesting structure types. Ba3GaQ4X (Q = S, X = Cl, Br; Q = Se, X = Cl) contain zigzag BaX pseudolayers and isolated GaQ4 tetrahedra, while Ba3InSe4Cl possesses one Ba-In-Se pseudolayer and one Ba-Cl pseudolayer, which are stacked alternately along the c-direction. Ba7In2Se6F8 is comprised of one-dimensional 1∞[InSe3]3- chains and unique [Ba7F8]6+ chains. In all those mixed anion compounds, the halide anions are only connected to alkaline-earth metal through strong ionic bonding, while the M (M = Ga, In) cations are only connected to chalcogenide anions through covalent bonding. UV-vis-NIR spectroscopy measurements indicate that Ba3GaQ4X (Q = S, X = Cl, Br; Q = Se, X = Cl) have band gaps of 2.14, 1.80, and 2.05 eV, respectively.

Optical transition probability of Er3+ ions in Er3+/Yb3+ codoped Ca3Ln2(BO3)4 (Ln=Y, Gd, La) crystals

Abstract This paper reports on the spectral parameters of Er3+ in Er3+/Yb3+ : Ca3Y2(BO3)4, Er3+/Yb3+ : Ca3Gd2(BO3)4 and Er3+/Yb3+ : Ca3La2(BO3)4 crystals. The results show that the oscillator strength parameters Ωt, fluorescence quantum efficiency and emission cross-sections of Er3+/Yb3+ : Ca3Ln2(BO3)4 (Ln=Y, Gd, La) crystals are larger than those of Er3+ : Ca3Ln2(BO3)4 (Ln=Y, Gd, La) crystals, and the codoped Er3+/Yb3+ can enhance the optical transition probability of Er3+ in the crystals and improve the fluorescence quantum efficiency and emission cross section of the 4I 13/2→4I 15/2 transition of Er3+ in Er3+/Yb3+ : Ca3Ln2(BO3)4 (Ln=Y, Gd, La) crystals.

Spectroscopic characteristics of Er3 +/Yb3 +:LiLa(WO4)2 crystal

Abstract The spectroscopic characteristics of Er3+/Yb3+:LiLa(WO4)2 crystal were investigated. Based on the Judd–Ofelt theory, the following intensity parameters Ωλ were obtained: Ω2=9˙03 × 10–20 cm2, Ω4=2˙02 × 10–20 cm2 and Ω6=0˙59 × 10–20 cm2. The upconversion emission of Er3+/Yb3+:LiLa(WO4)2 crystal was investigated under excitation with the 976 nm diode laser. The Er3+/Yb3+:LiLa(WO4)2 crystal has the intensity parameters Ωλ and a strong emission of 562 nm wavelength. Er3+/Yb3+:LiLa(WO4)2 crystal may be regarded as an upconversion laser material for the green light.

Growth and spectroscopic properties of Yb3+: Y0.8La0.2Ca4O(BO3)(3) crystal

Abstract A Yb3+:Y0·8La0·2Ca4O(BO3)3 crystal with the dimensions of ø16 × 20 mm has been grown by the Czochralski method. The absorption and emission cross-sections of the Yb3+:Y0·8La0·2Ca4O(BO3)3 crystals are 1·37 × 10−20 cm2 at 977 nm and 0·64 × 10−20 cm2 at 1033 nm respectively, which are larger than that of Yb3+:YCa4O(BO3)4 and Yb3+:GdCa4O(BO3)4 crystals. It shows that the spectroscopic properties of Yb3+:Y0·8La0·2Ca4O(BO3)4 crystal can be improved by substituting the part La3+ ions for the Y3+ ions in YCa4O(BO3)4 to form mixed YxLa1−xCa4O(BO3)3.

Spectroscopic characterisation of Yb3+-doped Sr2La0·667(VO4)2 crystal

Abstract A Yb3+ :Sr2La0·667(VO4)2 crystal with dimensions 18 × 15 × 30 mm3 has been grown by the Czochralski method. The absorption cross-section is 1·45×10−20 cm2 at 976 nm wavelength. The fluorescence spectrum exhibits a broad emission band from 925 nm up to 1125 nm and the emission cross-section is 0·64 × 10−20 cm2 at 1029 nm. The radiative and fluorescence lifetimes are 0·66 and 1·13 ms, respectively. In comparison with other Yb3+-doped materials, the value of I min of the Yb3+ :Sr2La0·667(VO4)2 crystal is lower, which implies that the Yb3+ :Sr2La0·667(VO4)2 crystal may possess a lower laser threshold.

Growth and spectroscopic properties of Nd3+/Yb3+-codoped Sr3Gd2(BO3)4 crystal

Abstract A Nd3+/Yb3+: Sr3Gd2(BO3)4 crystal 40 mm in diameter and 15 mm in height was grown by the Czochralski method. The spectroscopic characterization of Nd3+/Yb3+:Sr3Gd2(BO3)4 crystal was investigated. The emission crosssection of Yb3+ in the Nd3+/Yb3+:Sr3Gd2(BO3)4 crystal is 1·57 × 10−20 cm2 at 1014 nm, and the radiation lifetime τrad of 2F5/2 of Yb3+ is 881·6 μs. The result shows that the energy transfer occurs from 4F3/2 of Nd3+ to 2F5/2 of Yb3+ in the Nd3+/Yb3+:Sr3Gd2(BO3)4 crystal, which should enhance the laser efficiency of Yb3+ in the Nd3+/Yb3+:Sr3Gd2(BO3)4 crystal.

Structure, thermal and optical properties of Ca9Y0·5La0·5(VO4)7 – potential nonlinear optical material

Abstract The structure of a new nonlinear optical crystal, Ca9Y0·5La0·5(VO4)7, was solved, for first time to our knowledge. It belongs to trigonal system with space group R3c, its unit-cell parameters are: a = 10·8717(2) Å, c = 38·0753(14) Å, V = 3897·34(18) Å3, Z = 6, dc = 6·3279 g cm−3. The thermal expansion, the special heat capacity and the thermal conductivity of the crystal were investigated in detail. The crystal’s relative intensity for second harmonic generation is about 1·8 times as large as that of KH2PO4. Its transmittance exceeds 70% in the range of 400–2700 nm. From the measured principal refractive indices, the Sellmeier equations were derived. The results show that Ca9Y0·5La0·5(VO4)7 is expected to be a promising new frequency-doubling laser crystal.

Growth and spectroscopic characterisation of Tm3+/Yb3+ codoped LiGd(MoO4)2 crystal

Abstract The Tm3+/Yb3+:LiGd(MoO4)2 crystal with dimensions of Φ21 × 45 mm was grown by the Czochralski method. The spectroscopic properties of Tm3+/Yb3+:LiGd(MoO4)2 crystals were investigated. Based on the Judd–Ofelt theory, the oscillator strength parameters Ωt are: Ω2=16·468 × 10−20 cm2, Ω4=3·376 × 10−20 cm2, Ω6=2·613 × 10−20 cm2 for π-polarisation and Ω2=19·3 × 10−20 cm2, Ω4=1·582 × 10−20 cm2, Ω6=2·397 × 10−20 cm2 for σ-polarisation. The absorption cross-section σab are 4·17 × 10−20 cm2 at 796 nm and 5·31 × 10−20 cm2 at 797 nm for π- and σ-polarisation respectively. The emission cross-section σem are 1·72 × 10−20 cm2 at 1606 nm for π-polarisation and 2·00 × 10−20 cm2 at 1609 nm for σ-polarisation respectively. The Tm3+/Yb3+:LiGd(MoO4)2 crystals may be regarded as a potential infrared laser crystal.

Crystal growth and spectral properties of γ – Yb3 + : LaSc3(BO3)4

Abstract Aγ–Yb3+ : LaSc3(BO3)4 with a dimension of 30 × 20 × 10 mm has been grown from a mixed flux of Li6B4O9 and LiF by the top seeded solution growth method. The spectral properties have been investigated. The absorption and emission cross-sections of γ–Yb3+ : LaSc3(BO3)4 crystals are 1˙74 × 10−20 cm2 at 972˙3 nm and 8˙03 × 10−21 cm2 at 1026 nm respectively. The radiative lifetime and fluorescence lifetime of γ–Yb3+ : LaSc3(BO3)4 crystals are 0˙8 and 1˙658 ms respectively. The β min, l sat and l min are 9˙8%, 0˙7 kW cm−2 and 7˙1 kW cm−2 respectively. To sum up the spectral properties of γ–Yb3+ : LaSc3(BO3)4 crystal, it was suggested as a potential laser gain material.

Growth and spectral characteristics of KYb(WO4)(2) crystal

Abstract The present paper reports the growth and spectroscopic properties of KYb(WO4)2 crystal. The KYb(WO4)2 crystal with dimensions of 32 × 29 × 12 mm was grown from a mixed flux of K2WO4 and KF by the TSSG method. The spectroscopic properties of KYb(WO4)2 crystals were investigated. The absorption and emission cross-sections of KYb(WO4)2 crystal are 4˙32 × 10–20 cm2 at 981 nm and 3˙69 × 10–20 cm2 at 1024 nm for E//X polarisation respectively. The laser parameters of KYb(WO4)2 crystal were evaluated. These results suggest KYb(WO4)2 crystal as a potential candidate for microchip laser medium.