3 research outputs found
Evaluation of Growth, Thermal, and Spectroscopic Properties of Er3+-Doped CLNGG Crystals for Use in 2.7 ÎŒm Laser
A series of optical-quality Er3+-doped calcium lithium niobium gallium garnet (CLNGG) single crystals with different Er3+ ion concentration (10, 15 and 30 at.%) has been grown by the Czochralski method. A comparative study of their structure, thermal, and spectroscopic properties is performed. Crystal structure was analyzed with X-ray powder diffraction (XRPD) and refined by the Rietveld method, results showing that the Er:CLNGG crystal possesses a cubic structure with space group Ia3ÂŻd, and the lattice constants decrease linearly as the Er3+ concentration increase. The complete set of thermal properties were systematically studied for the first time. It has been found that all the thermal conductivities increase with temperature, indicating a glass-like behavior. Effect of Er3+ concentration on spectroscopic properties of Er:CLNGG crystals was studied. Results show that with the Er3+ concentration increase, the NIR fluorescence around 1600 nm weakens, while the Mid-IR fluorescence intensity around 2700 nm strengthens. Fluorescence lifetime of 4I13/2 decreased faster than that of 4I11/2 with the Er3+ concentration increase, which is beneficial for surmounting the âbottleneckâ effect to achieve 2.7 ÎŒm laser. All the results show that CLNGG crystal with high Er3+ concentration is a potential candidate for the 2.7 ÎŒm laser
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Tm3+-doped calcium lithium tantalum gallium garnet (Tm:CLTGG): novel laser crystal
We report on the development of a novel laser crystal with broadband emission properties at âŒ2 ”m â a Tm3+,Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr. 3ÂŻ, aâ=â12.5158(0) Ă
) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm-1K-1. Raman spectroscopy confirms a weak concentration of vacancies due to the charge compensation provided by Li+ codoping. The transition probabilities of Tm3+ ions are determined using the modified Judd-Ofelt theory yielding the intensity parameters Ω2â=â5.185, Ω4â=â0.650, Ω6â=â1.068 [10â20 cm2] and αâ=â0.171 [10â4 cm]. The crystal-field splitting of the Tm3+ multiplets is revealed at 10 K. The first diode-pumped Tm:CLTGG laser generates 1.08 W at âŒ2â
”m with a slope efficiency of 23.8%. The Tm3+ ions in CLTGG exhibit significant inhomogeneous spectral broadening due to the structure disorder (a random distribution of Ta5+ and Ga3+ cations over octahedral and tetrahedral lattice sites) leading to smooth and broad gain profiles (bandwidth: 130â
nm) extending well above 2â
”m and rendering Tm:CLTGG suitable for femtosecond pulse generation