Scientific Results

Multilayered YAG-Yb:YAG ceramics: manufacture and laser performance

Year: 2014

Authors: Esposito L., Hostaša J., Piancastelli A., Toci G., Alderighi D., Vannini M., Epicier T., Malchère A., Alombert-Goget G., Boulon G.

Autors Affiliation: CNR ISTEC, Inst Sci & Technol Ceram, I-48018 Faenza, RA, Italy; CNR INO, Ist Nazl Ott, I-50019 Sesto Fiorentino, FI, Italy; Materiaux, Ingenierie et Sciences (MATEIS), UMR 5510 CNRS, University of Lyon, F-69621 Villeurbanne, France; Institute Light Matter (ILM), CNRS-University Lyon 1, F-69622 Villeurbanne, France; ICT Prague, Department of Glass and Ceramics, Prague 16628, Czech Republic

Abstract: Thermal effects in transparent laser crystals and ceramics are generally an unwanted consequence of the pumping process: temperature gradients give rise to an unevenly distributed refractive index variation and a distortion of the optical surfaces crossed by the laser beam (thermal lens); birefringence due to thermomechanical stress can cause depolarization losses; and absorption from the ground level usually increases with temperature in quasi-three-level systems. All these effects can seriously impair laser performance, especially in high-power devices. Layered structures with a tailored modulation of the doping level can be used to reduce the peak temperature, the temperature gradients and also the thermally induced deformation of the laser material, thus mitigating the overall thermal effects. In the present work, structures comprising two and three layers of different compositions (pure YAG/10 at% Yb:YAG and pure YAG/10 at% Yb:YAG/pure YAG) were designed with a view to control deformation and stresses, and to reduce the thermal lensing effect. The multilayered samples were assembled by linear and cold isostatic pressing, and co-sintered under a high vacuum in a clean-atmosphere furnace. The microstructure of the layered samples obtained was characterized by FEG SEM, ESEM and TEM. The Yb diffusion profile across the doped/undoped interface was identified and related to the laser

Journal/Review: JOURNAL OF MATERIALS CHEMISTRY C

Volume: 2 (47)      Pages from: 10138  to: 10148

More Information: We acknowledge support from the bilateral \”SCOC\” project CNRS INSA Lyon-France/CNR ISTEC Faenza-Italy, the EC initiative \”LASERLAB-EUROPE\” (EC contract no. 284464) – Joint Research Activity WP33 – \”European Research Objectives on Lasers for Industry, Technology and Energy (EURO-LITE)\” and the Flag project RITMARE, La Ricerca Italiana per il Mare – coordinated by CNR and funded by the Ministry of Education, University and Research within the National Research Program 2011-2013. The authors thank the NanOpTec center of the UCB Lyon1, and especially Dr Gilles Ledoux, for access to their optical spectroscopy and confocal microscopy facilities.
KeyWords: Ceramic materials; Deformation; Laser beams; Lenses; Pressing (forming); Pumping (laser); Refractive index; Sintering; Thermal gradients; Vacuum furnaces; Ytterbium, Cold isostatic pressing; Deformation and stress; High-power devices; Quasi-three-level systems; Refractive index variations; Thermal lensing effect; Thermally induced deformations; Thermo-mechanical stress, Laser beam effects
DOI: 10.1039/c4tc01544d

Citations: 21
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