Scientific Results

Layered Yb:YAG ceramics produced by two different methods: processing, characterization and comparison

Year: 2016

Authors: HostaĊĦa J., Esposito L., Biasini V., Piancastelli A., Vannini M., Toci G.

Autors Affiliation: CNR ISTEC, National Research Council of Italy, Institute of Science and Technology for Ceramics, Via Granarolo 64, 48018 Faenza, Italy;
CNR INO, National Research Council of Italy, National Institute of Optics, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI) Italy

Abstract: The use of Yb:YAG ceramic gain media in solid state lasers has been of growing interest for high repetition rate and high power lasers. Probably the most important advantage of ceramic production technology in comparison with that of single crystals is the flexibility of shaping methods that allow the production of near-net-shape components with a welldefined internal structure. In the case of Yb:YAG with dopant distribution designed accordingly to the pumping and cooling geometry the efficiency of the laser device can be enhanced by mitigating thermal lensing effects. The presented work reports on Yb:YAG transparent ceramics composed of layers with different Yb doping produced by two different shaping methods: dry pressing of spray-dried powders and tape casting, all sintered under high vacuum. The selected geometry of materials was based on numerical simulations. Microstructure of the produced materials was characterized by SEM and EDX with a particular attention to the dopant content across the layers. The optical quality of produced ceramics was characterized and discussed in connection with the microstructure and laser emission results. Output power of nearly 7 W and slope efficiency 58.1 % were obtained in QCW regime from bilayered 0-10 %Yb:YAG. In the case of multilayered materials higher scattering losses were observed. The comparison between the two processing methods highlighted that the tape-cast materials provided higher optical uniformity and the diffusion zone between the single layers with different dopant content was about 150 nm compared to about 250 nm in samples produced by pressing of powders.

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KeyWords: Ceramic materials; Characterization; Crystal structure; Efficiency; High power lasers; Lasers; Microstructure; Multilayers; Powders; Processing; Pumping (laser); Single crystals; Sintering; Solid state devices; Ytterbium, High repetition rate; Multilayered materials; Near-net-shape components; Powder pressing; Tape casting; Thermal lensing effect; Transparent ceramic; Yb:YAG transparent ceramics, Solid state laser

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English