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A new Cr 3+ , Yb 3+ , Ho 3+ , and Pr 3+ co-doped GYSGG (Gd 2 YSc 2 Ga 3 O 12 ) single crystal with a size of Φ 26 mm × 80 mm was grown successfully using the Czochralski method for the first time. Absorption spectrum is studied, and main absorption bands are centered at 449, 638, and 934 nm. The fluorescence spectrum shows a broad emission band around 2.8 µm, indicating the Cr 3+ and Yb 3+ ions can act as the sensitizer for the Ho 3+ ions. The fluorescence lifetimes of the 5 I 6 and 5 I 7 levels of the Ho 3+ ions are fitted to be 0.39 and 5.31 ms, respectively. By comparison with those of the Cr,Yb,Ho:GYSGG crystal, the Pr 3+ ions acting as the deactivator can decrease efficiently the lifetime of the lower laser level 5 I 7 of the Ho 3+ ions. Additionally, a flash lamp pumping 2.84 µm laser with maximum average power of 257 mW is achieved. These results indicate the Cr,Yb,Ho,Pr:GYSGG crystal is a new promising radiation-resistant laser gain medium applied in radiant environment. [ABSTRACT FROM AUTHOR]

A novel mid-infrared (Er 0.3 Lu 0.1 Y 0.6) 3 Ga 5 O 12 laser crystal is successfully grown by the Czochralski method, the crystal structure, segregation coefficient, thermal performance, spectroscopy and 2.8 μm laser performance are studied systematically. The crystal possesses a pure garnet phase with a thermal conductivity of 4.54 W m−1 K−1. It exhibits a broader absorption band around 966 nm and some strong emission peaks at 2.6–3 μm, corresponding to the absorption cross-section of 1.39 × 10−21 cm2 at 966 nm and emission cross-section of 1.25 × 10−20 cm2 at 2822 nm, respectively. The level lifetimes of 4I 11/2 and 4I 13/2 are fitted to be 0.885 and 3.203 ms. A LD end-pumped Er:LuYGG laser has been demonstrated, achieving a maximum output power of 339 mW and a slope efficiency of 17.77 %. The primary laser wavelength is centered at 2824.76 nm. All the results indicate that the Er:LuYGG crystal is a novel and promising crystal material to realize the 3 μm laser. • A novel Er:LuYGG crystal is successfully grown by the Cz method. • Growth, thermal, spectroscopy and laser performance of Er:LuYGG crystals were studied. • A LD end-pumped Er:LuYGG laser is demonstrated with maximum output power of 339 mW. • The Er:LuYGG crystal is a potential and promising candidate to realize the 3 μm laser. [ABSTRACT FROM AUTHOR]

• Er,Pr:YAP crystals with two different Pr3+ concentrations are grown by CZ method. • Influence of Pr3+ concentrations on the luminescence and laser properties are investigated contrastively. • Watt-level ∼2.7 μm laser is achieved on the Er,0.1Pr:YAP crystal by LD end-pumping. • ∼2.7 μm laser power can be improved by optimizing the concentrations of deactivating Pr3+. High-quality Er,Pr:YAP crystals with two different Pr3+ concentrations are grown successfully, and the spectra and laser performances are studied in contrast. Both two crystals exhibit a wide absorption band with a central wavelength at 972 nm and high transmittance of over 80% in the wavelength range of 2.5 to 5 μm. The luminescence and laser properties are improved when the concentration of Pr3+ decreased from 0.2 at% to 0.1 at%. The maximum powers of 1040 and 835 mW are achieved in the Er,0.1Pr:YAP, and Er,0.2Pr:YAP crystals, corresponding to slope efficiencies of 13.97% and 10.94%, respectively. All the results indicate that co-doping with an appropriate concentration of deactivating Pr3+ is an effective method to attenuate the self-termination effect of Er3+, and then further improve the laser performance. [ABSTRACT FROM AUTHOR]

We demonstrate the influence of gamma-ray irradiation on the propagation loss and laser performance of an Er,Pr:GYSGG single crystal fiber (SCF). The size of SCF is Φ 0.75 mm × 70 mm and the diameter fluctuation is less than ±3.5%. The propagation loss coefficients of the samples are 0.07 and 0.09 dB cm−1 before and after irradiation, respectively, which is almost unaffected. The maximum output powers of 197 and 192 mW on the SCFs before and after irradiation are obtained under a 969 nm laser diode (LD) end-pumping, corresponding to the slope efficiencies of 8.1% and 7.9%, respectively. A very good beam quality factor M x 2 / M y 2 of 1.11/1.13 is achieved. These results imply that the Er,Pr:GYSGG SCF laser can be used as a potential seed source for mid-infrared (MIR) multi-stage amplification laser apparatus applied in radiation environment. • Er,Pr:GYSGG single crystal fiber (SCF) with a diameter of Ф 0.75 mm is prepared. • Effect of 100 Mrad 60Co gamma-ray irradiation on Er,Pr:GYSGG SCF is demonstrated. • Output power of 192 mW and M x 2 / M y 2 of 1.11/1.13 are achieved after irradiation. • Both maximum output power and slope efficiency are reduced by only 2.5%. • Er,Pr:GYSGG SCF laser is a potential seed light source applied in radiation environment. [ABSTRACT FROM AUTHOR]

We demonstrate the temperature distribution and 2.79 μ m laser performance in a high-quality Er:YSGG single crystal fiber (SCF) with size of Φ 0.85 × 8 mm3 for the first time. Compared with 2 × 2 × 8 mm3 Er:YSGG bulk crystal, the simulation results show that the center maximum temperature of Er:YSGG SCF is much lower, and the temperature rising and total thermal deformation are evidently reduced, indicating that the SCF possesses more efficient thermal dissipation. Under 970 nm laser diode pumping, a maximum output power of 636 mW with slope efficiency of 20.2% is realized. More importantly, a high beam quality factors M x 2 / M y 2 of 1.28/1.29 is obtained, which is close to the fundamental TEM 00 mode, suggesting that the Er:YSGG SCF can act as a promising candidate for mid-infrared laser seed source. • Er:YSGG single-crystal fiber(SCF) with a diameter of Φ 0.85 mm is prepared successfully. • Temperature distribution simulation shows the SCF possesses more efficient thermal dissipation. • 2794 nm CW laser power of 636 mW and beam quality factor M x 2 / M y 2 of 1.28/1.29 are achieved. • Er:YSGG SCF laser is a promising candidate for mid-infrared laser seed source. [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]

Er3+-doped YSGG crystals with nine different concentrations were grown successfully by Czochralski (Cz) method. The absorption, emission spectra, and the fluorescence decay curves are investigated comparably. Based on Judd–Ofelt (J–O) theory, the J–O intensity parameters Ω t (t = 2, 4, 6), the experimental and theoretical oscillator strengths are calculated with the absorption spectra. The results show that the 1 at. % lowly Er3+-doped YSGG crystal is more properly used in up-conversion laser applications and 5 at. % Er:YSGG crystal is a better candidate for 1.5 μm lasers within these nine crystals, while the heavily Er3+-doped YSGG crystal is beneficial for the 2.7 μm laser output. But if the doping concentration goes too high, the up-conversion rate of the 4I 11/2 level could be higher than that of the 4I 13/2 level, which would lead to increasing the up-conversion emission and quenching the mid-infrared emission. The 2.79 μm laser performance of LD end-pumped 40 at. % Er:YSGG crystal is also demonstrated. • Er:YSGG crystals with nine different concentrations were grown by Cz method. • The luminescence properties of Er3+ in YSGG crystals are fully researched. • 1 at. % Er:YSGG crystal is more suitable for up-conversion laser applications. • 5 at. % Er:YSGG crystal is a better candidate for 1.5 μm lasers. • A maximum power of 409 mW is obtained at LD end-pumped 40 at. % Er:YSGG. [ABSTRACT FROM AUTHOR]