Fabrication of sesquioxide (Yb:Lu2O3 and Yb:LuScO3) laser materials and their applications in high power ultrafast Thin-disk lasERs (“LuThER”)
Glass, Ceramics and Derived Composites
Final Report Abstract
The overall aim of the project was to develop sesquioxide crystals and ceramics and to investigate their suitability as gain media for thin-disk lasers. As a first step, extensive simulations of the expected laser performances were performed to define a favourable combination of doping level and thickness of the laser active media (LAM). The melt growth of the sesquioxide crystals was first tested using the floating-zone technique (FZT), resulting in small crystals that allowed for spectroscopic investigations, but were not suitable for thin-disk laser operation due to strong intrinsic tensions. Single crystals of undoped Lu2O3 and Sc2O3 were grown using the heatexchanger method (HEM). Unfortunately, the extremely high temperatures during crystal growth damaged the thermal insulation of the growth chamber, which limited further growth of crystals using the HEM within this project. More promising results were obtained by ceramic manufacturing, using wet-chemically precipitated nano powders followed by a vacuum sintering and hot-isostatic-pressure (HIP) sintering. About 60 pcs. of Yb:Lu2O3 and Yb:LuScO3 ceramics with diameters ranging from 12 mm to 16 mm were successfully fabricated. Spectroscopic measurements of the ceramics are shown in comparison to an already available Yb:Lu2O3 single-crystal which served as reference, unveiling the high optical quality of the ceramics. For continuous-wave (CW) multimode (MM) operation in a thin-disk oscillator, the Yb:Lu2O3 ceramics showed a performance comparable to the one of a single crystal with output powers exceeding 1 kW and slope efficiencies as high as 73 %. In fundamental-mode (FM) operation, the highest output power of 409 W was achieved using a 4 at.% Yb-doped Lu2O3 ceramic. The most promising disk (4 at.% Yb-doped Lu2O3 ) was tested in a mode-locked oscillator using a semiconductor saturable absorber mirror (SESAM). Stable mode-locked operation could, however, not be achieved, due to systematic damage of the SESAM. In addition, the Kerr-lens mode-locking (KLM) approach was tested, which led to a pulsing behaviour, which could, however, not be stabilized. Finally, a ceramic 4 at.% Yb-doped Lu2O3 disk was successfully tested in a thin-disk multipass amplifier (TDMPA) to amplify input pulses with a pulse duration of 530 fs at a repetition rate of 600 KHz. We could successfully amplify the pulses from an average power of 80 W to an average power of 180 W. This results in a pulse energy of 300 µJ and a peak power of 500 MW.
Publications
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Ceramic Yb:Lu2O3 thin-disk laser oscillator delivering an average power exceeding 1 kW in continuous-wave operation. Optics Letters, 46(24), 6063.
Esser, Stefan; Röhrer, Christian; Xu, Xiaodong; Wang, Jun; Zhang, Jian; Graf, Thomas & Ahmed, Marwan Abdou
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kW-class ceramic Yb:Lu2O3 thin disk laser. 2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 1-1. IEEE.
Esser, Stefan; Xu, Xiaodong; Zhang, Jian; Graf, Thomas & Ahmed, Marwan Abdou
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First thin-disk laser operation of ceramic Yb:LuScO3. Laser Congress 2023 (ASSL, LAC), AW3A.7. Optica Publishing Group.
Esser, Stefan; Jing, Wei; Xu, Xiaodong; Graf, Thomas & Ahmed, Marwan Abdou
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Single Crystalline and Ceramic Yb:Lu2O3 Gain Media in Thin-Disk Laser Operation. 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 1-1. IEEE.
Esser, Stefan; Xu, Xiaodong; Graf, Thomas & Ahmed, Marwan Abdou
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Single-crystal and ceramic Yb:Lu2O3 gain media for thin-disk oscillators. Applied Physics B, 129(10).
Esser, Stefan; Xu, Xiaodong; Wang, Jun; Zhang, Jian; Graf, Thomas & Abdou, Ahmed Marwan
