Scientific Results

Transparent layered YAG ceramics with structured Yb doping produced via tape casting

Year: 2016

Authors: Hostasa J., Piancastelli A., Toci G., Vannini M., Biasini V.

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

Abstract: The flexibility of the ceramic production process, in particular in terms of shaping and spatial control of distribution of active ions, is one of the strong points in favor of transparent ceramics. Iri high power lasers in particular, where thermal management is a critical issue, the finely controlled design of spatial distribution of the doping ions within the laser gain media can reduce undesired thermally induced effects and large temperature gradients, and thus enhance the efficiency and laser beam quality especially under increased thermal load. In the present work transparent Structured YAG ceramics with Yb doping were produced by tape casting followed by thermal compressioh of assembled tapes and sintered under high vacuum. The thermal compression of variously doped tape cast layers is a very promising method because it allows a high precision and good control over dopant distribution in the sintered material. After sintering, the distribution of Yb across the layers was characterized by SEM-EDX and the thickness of Yb diffusion zones between the layers with different Yb content was measured. Optical homogeneity was assessed by means of optical transmittance mapping of the samples and by 2D scanning of laser output. The effect of structured dopant distribution on laser performance was measured in quasi-CW and CW regime with different duty factors. Slope efficiency values higher than 50% were measured both in quasi-CW and in CW lasing conditions. The results are in good agreement with previously calculated predictions, confirming the beneficial effect of structured doping on laser performances and enlightening the impact of the residual scattering losses. Compared to other processing methods, such as the pressing of granulated powders, tape casting followed by thermal compression leads to straight and narrow interfaces between layers with different composition and allows to build structures composed of extremely thin layers with defined dopant content. (C) 2016 Elsevier B.V. All rights reserved.

Journal/Review: OPTICAL MATERIALS

Volume: 65      Pages from: 21  to: 27

More Information: The authors gratefully acknowledge the support from the Italian Ministry of Defence under PNRM, Contract No. 8723 of 19/12/2014 (CeMiLAP) and thank Paola Pinasco for assistance with tape casting and Laura Esposito for her support.
KeyWords: Laser gain media; Tape casting; YAG; Yb:YAG; Ceramic materials; Doping (additives); Efficiency; High power lasers; Laser beams; Quality control; Sintering; Solid state lasers; Ytterbium, Ceramic production process; Laser gain media; Layered Structures; Optical homogeneity; Residual scattering; Tape casting; Thermal compressions; Transparent ceramic, Laser beam effects
DOI: 10.1016/j.optmat.2016.09.057

Citations: 5
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