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The spectral properties of lightly doped Er:CaF 2 and Er,Pr:CaF 2 single crystals were investigated. Benefited from particular clustering effect, 2.79 μm continuous-wave (CW) laser operation was demonstrated in lightly doped 3 at.% Er:CaF 2 crystal. After co-doping small amount of Pr 3+ , the lifetime gap between Er 3+ : 4 I 11/2 and Er 3+ : 4 I 13/2 was shortened from 7.86 ms to about 1 ms. Moreover, the near-infrared and up-conversion fluorescence were significantly quenched. Thus, the CW laser performance was greatly improved. The slope efficiency was effectively improved from 8.0% to 15.8%. [ABSTRACT FROM AUTHOR]

Tm3+-doped calcium niobium gallium garnet (Tm:CNGG) single crystals have been successfully grown by the micro-pulling-down (μ-PD) method. The crystal structure, absorption spectra, fluorescence spectra and lifetimes of Tm:CNGG crystals were investigated. The absorption and emission bandwidths of Tm:CNGG crystals are larger than those of other Tm3+ doped garnet crystals, which will be beneficial for laser diode (LD) pumping and ultrashort pulse generation. Additionally, continuous wave (CW) laser operation around 2 μm was achieved in the 2.0 at.% Tm:CNGG crystal by LD pumping. [ABSTRACT FROM AUTHOR]

Tm3+, Pr3+ co-doped Bi 4 Ge 3 O 12 (Tm,Pr:BGO) crystals with various Pr3+ doping concentration were successfully grown using the micro-pulling-down (μ-PD) method. The use of Pr3+ co-doping for deactivating the Tm3+ ions at 1.5 μm emission was investigated in the BGO single crystal for the first time. The effect of Pr3+ concentration on the spectroscopic properties of Tm,Pr:BGO crystals were demonstrated. In addition, the fluorescence lifetime of Tm3+:3F 4 level of 0.5 at.% Pr, 2 at.% Tm:BGO crystal was quenched effectively (from 5.64 ms down to 0.36 ms) and the population inversions between Tm3+:3H 4 and 3F 4 levels are enhanced to achieve a four-level laser system at 1.5 μm. • Tm,Pr:BGO crystals with different Pr3+ concentration were grown using by the micro-pulling-down method. • The effect of Pr3+ concentration on the spectroscopic properties of Tm,Pr:BGO crystals was studied. • The use of Pr3+ co-doping for deactivating the Tm3+ ions at 1.5 μm emission was investigated in BGO crystal. [ABSTRACT FROM AUTHOR]

A Nd:BGSO crystal with the dimensions of Φ2 × 131 mm3 has been grown successfully by the micro-pulling-down method. The peak absorption cross-section at 808 nm was calculated to 0.98 × 10−20 cm2 with full-width at half-maximum of 17.4 nm. The stimulated emission cross-section was obtained to be 3.15 × 10−20 cm2 at 1063 nm. The fluorescence and radiative lifetimes of 4F 3/2 level were 248 μs and 300 μs respectively. All results indicate that the Nd: BGSO single crystal would be a promising near-IR solid-state laser material. [ABSTRACT FROM AUTHOR]

GdScO 3 single crystal codoped with Tm3+ and Tb3+ ions was successfully grown by the Edge-defined Film-fed Growth Method (EFG) for the first time. Absorption, fluorescence spectrum and fluorescence lifetimes of the grown crystal at room temperature were measured. The absorption cross-section at 789 nm was calculated to be 8.20 × 10−21 cm2. The emission cross-section was 1.35 × 10−21 cm2 at 1504 nm with the FWHM of 95.3 nm. The fluorescence lifetimes of the 3H 4 state and the 3F 4 state were fitted to be 253 μs and 1460 μs, respectively. Compared with Tm3+ single doped GdScO 3 crystal, the codoping of Tb3+ successfully depopulated the 3F 4 energy level and enhanced the emission at 1.5 μm region. It indicated that Tm,Tb:GdScO 3 could be favorable laser medium for 1.5 μm-laser operation. • Tm3+ and Tb3+ co-doped GdScO 3 crystal was successfully grown by the edge-defined film-fed method (EFG) for the first time. • Spectral parameters and Judd-Ofelt parameters of Tm,Tb:GdScO3 crystal were obtained and compared. • The fluorescence mechanism of Tm3+ and Tb3+ co-doped GdScO 3 crystal has been studied. [ABSTRACT FROM AUTHOR]

Nd3+ doped Y 3 Sc x Al 5-x O 12 (x = 0.05, 0.5, 1) single crystals were successfully grown by the micro-pulling-down (μ-PD) technique. The effect of compositional parameter x on the structure, absorption, emission and fluorescence lifetime of Nd:Y 3 Sc x Al 5-x O 12 crystals was studied. The Nd3+ concentration in the core increased with increasing of compositional parameter x. The full width at half maximum (FWHM) of the emission band centered at 1064 nm was calculated to be 6.1, 7.1, and 7.3 nm for x = 0.05, 0.5 and 1, respectively. The fluorescence lifetimes of 4F 3/2 levels are 259.3, 269.6, and 276.9 μs for x = 0.05, 0.5, and 1, respectively. The results indicate that the Nd:Y 3 Sc x Al 5-x O 12 crystals are promising materials for laser output. • Nd:Y 3 Sc x Al 5-x O 12 crystals were successfully grown by the micro-pulling-down technique. • Spectral parameters of Nd:Y 3 Sc x Al 5-x O 12 crystals were obtained. • The effect of composition on the structure and spectral parameters was discussed. [ABSTRACT FROM AUTHOR]

High optical quality Er3+ doped Lu 2 O 3 single crystal with optimum doping concentration was grown by Floating zone (Fz) method. The spectral properties and Judd-Ofelt (JO) analysis were reported. The emission cross-section at 2772 nm was calculated to be 2.47 × 10−20 cm2 with FWHM of 188 nm. The fluorescence lifetime of 4I 11/2 and 4I 13/2 energy level was fitted to be 1.62 ms and 4.02 ms. Optimum lifetime ratio (τ low /τ up) is beneficial to laser operation. Compared with reported Er3+ doped crystal, the larger spectral quality factors Q and low inversion ratio P of 7 at.% Er:Lu 2 O 3 crystal indicate that it has a favorable laser performance for 2.8 μm laser operation. • In our work high optical quality 7 at.% Er3+ doped Lu 2 O 3 single crystal with optimum doping concentration was grown by Floating zone method. • The spectroscopic properties were reported by Judd-Ofelt theory. • In order to weaken the influence of reabsorption phenomenon, we grind sample of Er:Lu 2 O 3 crystal into powder to measure fluorescence lifetime of 4I 13/2. • The measured fluorescence lifetime of 4I 13/2 is close to actual value. • We compare the optical characteristics of 7at.% Er:Lu 2 O 3 crystal with other materials in Mid-infrared. [ABSTRACT FROM AUTHOR]