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Lu 2.4 Y 0.6 Al 5 O 12 (LuYAG) crystals with three different doping concentrations of Tm 3+ and Ho 3+ were grown successfully by the Czochralski method. The crystals exhibit broad absorption band at 783 nm and the full width at half maximum (FWHM) are about 11 nm. Excited by 783 nm laser diode (LD), strong fluorescence peaks are observed near 2.9 μm, suggesting that the Tm 3+ ions can act as the sensitizer for Ho 3+ ions. The stimulated emission cross-sections at 2.911 μm are calculated to be 5.49 × 10 −18 cm 2 , 3.11 × 10 −18 cm 2 , and 4.04 × 10 −18 cm 2 , respectively. Compared with the Tm,Ho:LuAG, and Tm,Ho:YAG crystals, the Tm,Ho:LuYAG crystal with 3 at.% Tm 3+ and 1 at.% Ho 3+ has a relatively longer lifetime 0.138 ms for the upper level 5 I 6 and a shorter lifetime 7.25 ms for the lower level 5 I 7 , which is advantageous to the population inversion. These results indicate that the Tm,Ho:LuYAG crystal with 3 at.% Tm 3+ and 1 at.% Ho 3+ is a new potential candidate for realizing the 2.911 μm laser output. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new Cr,Yb,Ho,Eu:YAP laser crystal was grown by the CZ method for the first time. [•] Thermal properties indicate the suitable crystal growth direction is the b axis. [•] Spectroscopic measurements show Cr3+ and Yb3+ can act as sensitizers of Ho3+ ions. [•] Eu3+ ions can act as deactivator in decreasing threshold and increasing efficiency. [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]

We investigate the defect, mechanical, thermal properties, and refractive index of Er:LuYSGG mixed crystal grown by the Czochralski method. The chemical etching pit patterns present a regular tetrahedron, which consists well with the corresponding atomic arrangement schematics. The Mohs hardness is obtained to be 6.60. The thermal expansion coefficient and the thermal conductivity along <111> crystallographic orientation are achieved to be 7.91 × 10−6 K−1 and 3.423 W m−1 K−1, respectively, indicating the Er:LuYSGG has a relatively high damage threshold. Based on the measured values of refractive index, the Sellmeier equation is fitted and the refractive index curve in the range of 400–3000 nm is displayed. All these results are of great significance for the further research and laser application of Er:LuYSGG crystal. • Physical and chemical properties of Er:LuYSGG laser crystal are investigated in detail. • Mohs hardness and thermal expansion coefficient are obtained to be 6.60 and 7.91 × 10−6 K−1. • A high thermal conductivity of 3.423 W m−1 K−1 is conducive to heat dissipation. • Sellmeier equation and refractive index curve are fitted using the measured values. • Results can provide useful parameters for laser application of Er:LuYSGG crystal. [ABSTRACT FROM AUTHOR]

Abstract Er3+ and Pr3+ co-doped YAP laser crystal with high optical quality was grown successfully by the Czochralski method for the first time. By contrast, an Er3+ single doped YAP laser crystal was also grown. The cell parameters of the two crystals were obtained by the X-ray Rietveld refinement method. The X-ray rocking curves indicate that the as-grown crystals possess excellent crystalline quality. The absorption spectra show that the crystals are suitable to be pumped by 972 nm LD. The NIR and MIR emission spectra, the up–conversion spectra and the fluorescence decay curves were also measured to investigate the influence of Pr3+ ions on the spectroscopic properties. The results indicate the Pr3+ ions acting as the deactivator can decrease efficiently the lifetime of the lower laser level 4I 13/2 of the Er3+ ions from 10.72 to 0.489 ms, which would be beneficial to decrease the laser threshold and increase the laser conversion efficiency. Highlights • XRCs show Er:YAP and Er,Pr:YAP crystals possess high crystalline quality. • Pr3+ deactivator reduces 4I 13/2 lifetime from 10.72 to 0.489 ms, benefiting to decrease threshold and improve efficiency. • NIR and UC fluorescence provide further evidence that Pr3+ ions can efficiently depopulate Er3+ ions at 4I 13/2 level. • All results indicate the Er,Pr:YAP crystal is a promising laser medium for realizing a 2.7 μm laser pumped by 970 nm LD. [ABSTRACT FROM AUTHOR]