11 W continuous-wave laser operation at 2.09 μm in Tm:Lu1.6Sc0.4O3 mixed sesquioxide ceramics pumped by a 796 nm laser diode

High quality thulium doped Lu1.6Sc0.4O3 mixed sesquioxide laser ceramics were fabricated using a solid-state reactive sintering method. Optical and spectroscopic properties of the ceramics were studied. A high transmittance almost identical to the theoretical value of the ceramics was reached at the lasing wavelength. A large Stark splitting of 920 cm(-1) for the ground states H-3(6) and 472 cm(-1) for the first excited states F-3(4) of Tm3+ were observed, resulting in a long wavelength emission band around 2.09 pm with low reabsorption losses at this wavelength. CW laser operation at 2.09 pm pumped by a 796 nm laser diode was achieved with an output power of 11 W and an optical-to-optical conversion efficiency of 28.9%, both of which are the highest values reported so far for lasing around 2.1 mu m in Tm3+ doped mixed sesquioxide ceramics. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement