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The laser efficiency increased with increasing doping concentration from 0.2% to 5%, while a Tm:Lu2O3 crystal exhibited a lower efficiency, which can be attributed to thermal problems. A 1% thulium doped crystal, which was grown by the heat-exchanger-method, showed much less stress than the other crystals, leading to a significantly higher slope efficiency than for a Nacken-Kyropoulos-crystal with...
Transient Yb2+ states the role of permanent Yb2+ states is discussed. Investigations on Yb:YAG single crystals grown in reducing atmosphere reveal that the magnitude of photocurrent is reduced by annealing the sample. This result points towards an involvement of permanent Yb2+ states in the photoconductivity mechanism. To further examine the influence of Yb2+-ions, samples with Si4+ co-doping are...
The energy transfer from Yb3+ to Er3+ in crystalline Sc2O3 is studied using continuous wave (cw)-excitation method and Yb3+ ions excitation in the sample by pulsed optical parametrical oscillators. Crystalline Sc2O3 films with different Er3+ and Yb3+ concentrations are grown on alpha-Al2O3 substrates by pulsed laser deposition. Laser-experiments with codoped Er3+(0.23%),Yb3+(0.4%):Sc2O3 and Er3+(0...
At high Er3+ doping, electric dipole-dipole interactions between neighboring ions such as energy migration and energy-transfer upconversion (ETU) take place, thereby reducing the population inversion and negatively affecting the gain performance of the amplifier. These effects are investigated by lifetime and gain measurements respectively, in Al2O3:Er3+ waveguides and analyzed the results in the...
This work presents a clear improvement of the crystal growth by the heat exchanger method (HEM) leading to longer fluorescence lifetime and higher laser efficiency of this material. Polycrystalline boules of 40 mm diameter and 25 mm length with monocrystalline regions of up 5 cm3 have been grown with 6N LU2O3 and 5N Yb2O3 in a 40 mm diameter high purity Re-crucible under H2/N2 atmosphere. The fluorescence...
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