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An Er:Y3Ga5O12 crystal doped with 30 at% Er3+ was grown by the Czochralski method. The crystal structure and component, thermal and spectroscopic properties are studied systematically. The laser performance of a Φ 3 mm × 66 mm Er:YGG crystal was investigated with LD side-pumped method in the CW mode. The maximum output power of 7.25 W is much higher than that has been realized in the LD end-pumped Er:YGG crystal. The results indicate that the Er:YGG crystal is an ideal material to realize 3 μm laser and the LD side-pumping is a preferred approach to achieve high-power CW laser. [ABSTRACT FROM AUTHOR]

Tm3+ doped YAlO3 (Tm:YAP) crystals with different concentrations were grown successfully by Czochralski method. The full width at half maximum of 0.007–0.008° shows high crystalline quality. The shape of dislocation etching pit is consistent with its crystal structure. The absorption spectra show an intensive peak located at 794 nm. The fluorescence lifetimes of 6.06, 4.68, 4.22, 4.01, and 1.93 ms decrease monotonically with the increase of Tm3+ concentration in the range of 2–7.5 at%. The fluorescence spectra exhibit two strong peaks appeared near 1775 and 1853 nm, respectively. Among them, the 4 at.% Tm:YAP crystal possesses the largest fluorescence intensity at 1853 nm, indicating that it is a promising gain material operated at ~ 1.9 μm for the development of diode-pumped solid-state lasers and the dopant concentration larger than 4 at.% may cause decline in laser performance owing to larger reabsorption loss and higher nonradiative decay rate. [ABSTRACT FROM AUTHOR]

A new laser crystal from Lu2.4Y0.6Al5O12 (LuYAG) co-doped with Cr3+, Tm3+, Ho3+, and Pr3+ ions was grown successfully by the Czochralski method for the first time. The structure parameters of the Cr,Tm,Ho,Pr:LuYAG crystal are determined by the X-ray Rietveld refinement method. The main absorption bands are observed near 426 and 782 nm, and the fluorescence spectrum excited by a 450 nm or 783 nm LD presents an emission band near 2.911 μm, indicating that the co-doped Cr3+ and Tm3+ ions can be utilized as sensitizers for the Ho3+ ions. The lifetimes of the 5I6 and 5I7 levels of the Ho3+ ions were measured and fitted to be 0.070 ms and 1.852 ms, respectively. The energy transfer efficiencies of the processes 5I6 (Ho3+) →3F3,4 (Pr3+) and 5I7 (Ho3+) →3F2 (Pr3+) + 3H6 (Pr3+) were calculated, showing that the Pr3+ ions can play the role of a deactivator for the Ho3+ ions. Furthermore, the energy transfer mechanisms among the Cr3+, Tm3+, Ho3+, and Pr3+ ions were studied. The results suggest that the Cr,Tm,Ho,Pr:LuYAG crystal is a new promising laser medium operating at around 2.9 μm under flash lamp or 783 nm LD pumping. [ABSTRACT FROM AUTHOR]

• Influence of 60Co gamma-ray irradiation on the Er:LuYSGG crystal was demonstrated. • Maximum average output power of 886 mW is achieved after irradiation. • Maximum output power and slope efficiency are reduced by only 2.5% and 3.7%. • Lifetime ratio between lower and upper laser levels is reduced after irradiation. • Er:LuYSGG crystal is a potential 2.79 μm radiation-resistant laser material. We demonstrate the influence of gamma-ray irradiation on the structure, spectroscopies, and laser performance of Er:LuYSGG crystal. After 100 Mrad 60Co gamma-ray irradiation, the crystal structure remains unchanged, the absorption near 968 nm and emission within 2.7 ∼ 3 μm are almost unaffected, the level lifetimes are reduced, and the maximum output power of 886 mW is achieved with a maximum slope efficiency of 20.8%. The maximum output power and slope efficiency decrease by only 2.5% and 3.7% after irradiation, respectively, and the M 2 factor is little affected by irradiation. The results indicate that the Er:LuYSGG crystal is a potential mid-infrared radiation-resistant laser material applied in radiation environments. [ABSTRACT FROM AUTHOR]

Structure, defects, and spectroscopic properties of a Yb,Ho,Pr:YAlO 3 (Yb,Ho,Pr:YAP) single crystal grown by the Czochralski method were investigated. The effective segregation coefficients of the Yb 3+ , Ho 3+ , and Pr 3+ ions are 1.06, 1.32, and 0.90 in YAP host, respectively. The structural parameters are obtained by the X-ray Rietveld refinement method. A high crystalline quality of the Yb,Ho,Pr:YAP is determined by the X-ray rocking curve. The dislocations of (100), (010), and (001) faces are studied using the chemical etching with the phosphoric acid etchant. The absorption spectra show that there exists strong absorption in the wavelength range of 900–1000 nm, and the fluorescence spectrum excited by 970 nm LD presents that the strongest emission is located at 2853 nm, indicating the Yb 3+ ions can be acted as the sensitizer for the Ho 3+ ions. The level lifetimes indicate that the Pr 3+ ions can play a deactivator role for the Ho 3+ ions. All these results imply that the Yb,Ho,Pr:YAP crystal can be regarded as a promising candidate for realizing 2.8–3.1 μm laser output. [ABSTRACT FROM AUTHOR]

A Nd3+-doped Y 2.8 ScAl 4.2 O 12 (Nd:YSAG) single crystal was grown successfully via the Czochralski technology. The crystal structure and crystalline quality of the as-grown Nd:YSAG crystal were determined by the X-ray powder diffraction and X-ray rocking curve, respectively. By X-ray fluorescence analysis, the effective segregation coefficient of Nd3+ is calculated to be 0.33 in the YSAG crystal. Using the chemical etching method, the dislocation density on the (111)-crystalline face is obtained to be about 3.45 × 102 cm−2. The large absorption cross-section (2.95 × 10−20 cm2) and wide FWHM (9.8 nm) around 808.8 nm imply a high LD pumping efficiency. The high emission cross-section (3.53 × 10−20 cm2) at 1336.3 nm and long fluorescence lifetime of Nd3+ ions (286.20 μs) are beneficial to realize laser output. Thereby, all the results indicate that the Nd:YSAG crystal is a potentially new gain material pumped by a LD for near-infrared laser at 1336.3 nm. • A Nd3+:Y 2.8 ScAl 4.2 O 12 crystal was grown successfully by the Czochralski method. • Dislocation density on the (111)-crystalline face is obtained to be 3.45 × 102 cm−2. • A large absorption cross-section (2.95 × 10−20 cm2) implies high pumping efficiency. • High emission cross-section (3.53 × 10−20 cm2) is beneficial to realize 1336.3 nm laser. • All results indicate this crystal is a potential gain material for 1336.3 nm laser. [ABSTRACT FROM AUTHOR]

Five substituted gadolinium gallium garnet crystals with different Ca2+/Mg2+/Zr4+ stoichiometric ratio concentrations (Zr4+: 13.0, 15.0, 15.3, 16.3, 19.5 at.%, as well as increasing Ca2+ and Mg2+ concentrations in proportion) were grown by Czochralski technique. Their structure, defect, thermal and optical properties were comparatively studied and analyzed. The lattice parameters are achieved to be 12.47–12.54 Å which are 0.7–1.2 % larger than that of Gd 3 Ga 5 O 12. A linear equation with Zr4+ concentration is fitted to adjust the lattice parameter for demand. X-ray rocking curves with narrow FWHMs of 1.67′, 1.97′, 1.75′, 2.12′, 2.99′, respectively, indicating high crystalline quality when the Zr4+ concentration is below 16.3 at.%. The dislocation densities are 62, 47, 63, 315 and 3184 cm−2, suggesting the value increases rapidly when the Zr4+ concentration exceeds 16.3 at.% due to large lattice distortion. The thermal expansion coefficients are about 8.55 × 10−6 to 8.72 × 10−6 K−1, respectively. All the transmittances are above 80 % from visible to infrared wavelengths, and Sellmeier coefficients of refraction index equation were fitted, which is benefit for CaMgZr:GGG as substrate and optics application. The above results suggest that a more suitable substrate can be obtained for the series YIG magnetic-optic thin films by optimizing the Ca2+/Mg2+/Zr4+ concentrations. ● Five SGGG single crystals with different Ca2+/Mg2+/Zr4+ concentrations were successfully grown by Cz method. ● Relationship of concentrations and lattice constants can be described by fitting equation to adjust lattice parameter better. ● The Ca2+/Mg2+/Zr4+ concentrations have significative effect on crystalline quality, dislocation density and thermal expansion. ● Experimental refractive index and energy gaps data for different SGGG single crystals are provided. ● Potential and economic application value of SGGG in laser gain medium or substrate for series YIG magneto-optical thin films. [ABSTRACT FROM AUTHOR]

A series of Ho and Pr doped LuYSGG laser crystals were successfully grown by Czochralski method. X-ray rocking curves indicate their high crystalline quality. Crystal structure and basic parameters are provided by XRD and Rietveld refinement. Combining density functional theory, the bandgaps of YSGG and LuYSGG are calculated to be 3.497 and 3.483 eV, respectively. Particularly, the J-O parameters and emission spectra suggest the LuYSGG is more suitable as host for Ho3+ ions and could achieve better 2.9 μm emission than the YSGG. Meanwhile, the luminescent decay curves show the deactivated Pr3+ ion can greatly narrow the lifetime gap between the 5I 6 and 5I 7 energy levels, which can eventually attenuate effect of self-termination phenomenon on the 2.9 μm emission. • A series of Ho and Pr doped LuYSGG mixed laser crystals are prepared. • Microscopic and bandgap structure of LuYSGG are investigated in detail. • LuYSGG is more suitable for achieving Ho:2.9 μm emission than YSGG. • Pr can effectively attenuate the 2.9 μm self-termination phenomenon. [ABSTRACT FROM AUTHOR]