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Highlights • High quality Cr,Er:YAG crystal was grown successfully by the Czochralski method. • Maximum single-pulse energies of 0.99 and 1.52 J are obtained on Er:YAG and Cr,Er:YAG. • Slope efficiencies are 1.31% and 1.80% for Er:YAG and Cr,Er:YAG, respectively. • Cr3+ can improve laser efficiency of Cr,Er:YAG without affecting beam quality. • Cr,Er:YAG may be a potentially mid-infrared radiation-resistant laser material. Abstract We demonstrated an improvement of laser performance by co-doping Cr3+ into Er:YAG crystal grown by the Czochralski method. The result of X-ray rocking curve suggested that the crystal had high crystalline quality. Two strong absorption bands centered at 450 and 596 nm indicated the Cr,Er:YAG crystal was more suitable for xenon lamp pumping. A maximum single pulse energy of 1.52 J was obtained on the Cr,Er:YAG crystal operated at 5 Hz and 2.94 μm, corresponding to the slope efficiency and electrical-to-optical efficiency of 1.80% and 1.28%, but those of the Er:YAG crystal were only 0.99 J, 1.31% and 0.83%, respectively. Therefore, the Cr,Er:YAG crystal may be a potentially mid-infrared radiation-resistant laser material with higher single pulse energy and efficiency. [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]

A novel Yb,Ho,Pr:LuYAG laser crystal was successfully grown and investigated in detail, which belongs to the cubic system with a space group of I a-3d. The X-ray rocking curve of the as-grown crystal implied high crystalline quality. The dislocation defects were revealed by the chemical method. Moreover, the density, thermal expansion coefficient and thermal conductivity were determined. The absorption coefficient at 935 nm and the emission cross-section at 2.911 μm were obtained to be about 15.18 cm−1 and 2.23 × 10−21 cm2, respectively. The lifetime of the lower laser level 5I 7 was shown to decrease from 7.58 to 5.88 ms, while that of the upper laser level 5I 6 basically remained unchanged, suggesting that the co-doped Pr3+ possessed an efficient deactivation effect and was beneficial in attaining population inversions of Ho3+. The corresponding findings illustrate that the Yb,Ho,Pr:LuYAG crystal can serve as a novel promising gain medium for realizing the 2.911 μm laser pumped by ~ 940 nm high-power InGaAs laser diode. • A novel Yb,Ho,Pr:LuYAG laser crystal was successfully grown by Czochralski method. • The crystal possesses a high thermal conductivity, which is helpful in dissipating heat during laser action. • Yb3+ makes the crystal suitable for 935 nm LD pumping and Pr3+ can inhibit self-termination phenomenon. • High absorption coefficient at 935 nm and large emission cross-section at 2911 nm are beneficial in realizing ∼2.9 μm laser. • The Yb,Ho,Pr:LuYAG crystal is a new promising gain medium for realizing 2.911 μm laser. [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]

Er3+-doped YAP crystals with concentrations of 5 at%, 10 at%, 15 at% and 20 at% were grown successfully by Czochralski method. X-ray rocking curves suggest high crystalline quality. Lifetime ratio of 4I 13/2 and 4I 11/2 levels decreases obviously with the increase of Er3+ concentrations, which is beneficial to realize population inversion and decrease the laser threshold. Spectroscopy and laser show the 15 at% Er:YAP crystal has strongest mid-infrared fluorescence intensity and best laser performance by 968-nm LD side-pumping. Maximum average powers of 23.52 and 11.08 W are achieved at 250 and 1000 Hz, corresponding to the slope efficiency of 12.0% and 6.2%, respectively. Therefore, the 15 at% Er:YAP crystal is a promising candidate for the high-power and high-frequency mid-infrared laser. • High-quality Er:YAP crystals with four concentrations were grown by the Cz method. • Influences of Er3+ concentrations on the performance of Er:YAP crystals were studied. • Energy transfer and luminescence mechanism in the Er:YAP crystals were analyzed. • LD side-pumped high-power and high-frequency Er:YAP laser is demonstrated. • Maximum average power of 23.52 W was obtained on the 15 at% Er:YAP crystal. [ABSTRACT FROM AUTHOR]

We demonstrate a high-peak-power and narrow pulse mid-infrared (MIR) laser with xenon-lamp pumping and La3Ga5SiO14 (LGS) Q-switching on the Cr,Er:YAP crystal grown by Czochralski method. X-ray powder diffraction and x-ray rocking curves suggest the crystal has high crystalline quality. Segregation coefficients of the Cr3 + and Er3 + in the as-grown Cr,Er:YAP crystal are 4.96 and 1.07, respectively. The absorption and fluorescence spectra indicate that the Cr,Er:YAP crystal is a promising material for MIR laser by xenon-lamp pumping. The fluorescence lifetimes of the upper (I11/24) and lower (I13/24) laser levels are 0.86 and 3.57 ms, respectively. A maximum energy of 632 mJ is acquired at 5 Hz by xenon lamp pumping. By the LGS electro-optic Q-switching technology, single pulse energy of 148.6 mJ is achieved at 5 Hz with a pulse width of 35.4 ns and peak power of 4.2 MW. The results show that the LGS Q-switched Cr,Er:YAP crystal pumped by xenon lamp possesses potential application as a short-pulse and high-energy laser device. [ABSTRACT FROM AUTHOR]

We report on the spectroscopic and laser performance of a novel 30 at.% Er:LuYSGG mixed crystal grown by Czochralski method. The XRC result shows the crystal has a high crystalline quality. A strong absorption peak is located at 966 nm with a FWMH of about 11 nm. The lifetimes of the upper 4I 11/2 and lower 4I 13/2 levels are 1.91 ms and 6.53 ms, respectively. A maximum output power of 909 mW with LD end-pumping is achieved, corresponding to optical-to-optical conversion efficiency of 18.1% and slope efficiency of 21.6%. The laser wavelength of 2794 nm and beam quality factors M x 2 /M y 2 of 1.78/1.83 are displayed. These results indicate that Er:LuYSGG mixed crystal is a promising gain medium for 2.8 μm laser. • The Er:LuYSGG mixed crystal with high optical quality was grown by the Cz method. • It has a longer upper laser level lifetime of 1.91 ms. • A maximum output power of 909 mW with LD end-pumping was obtained. • Results indicate the Er:LuYSGG is a promising gain medium for 2.8 μm laser. [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]