Laser and optical properties of Yb:YAG ceramics with layered doping distribution: design, characterization and evaluation of different production processes

Anno: 2016

Autori: Toci G., Lapucci A., Ciofini M., Esposito L., Hostaša J., Gizzi L. A., Labate L., Ferrara P., Pirri A., Vannini M.

Affiliazione autori: CNR – INO National Research Council, National Institute of Optics, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI) Italy;
CNR – INO National Research Council, National Institute of Optics, Largo Enrico Fermi 6, I-50125 Firenze, Italy;
CNR – ISTEC National Research Council, Institute of Science and Technology for Ceramics, Via Granarolo 64, 48018 Faenza, Italy;
CNR – INO National Research Council, National Institute of Optics, Via G. Moruzzi, 1, I-56124 Pisa, Italy;
CNR – IFAC National Research Council, Institute of Applied Physics “Nello Carrara”, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI) Italy

Abstract: The laser, optical and spectroscopic properties of multilayer Yb:YAG ceramic structures, differently activated, were investigated. The structures were designed by means of Finite Element Modeling, adjusting the doping distributions to reduce peak temperature, surface deformation and thermally induced stresses, depending on the pump and cooling geometry.
Two ceramic processes were used, i.e. dry pressing of spray-dried powders (SD) and tape casting (TC), resulting in different defect density and size distribution: TC gives a more uniform transmission, whereas SD results in larger, unevenly scattered defects. The spectroscopic properties were found independent from the production process. The laser performance has been characterized under high intensity pumping in a longitudinally diode pumped laser cavity, comparing the behavior of the different structures in terms of slope efficiency, stability under increasing Thermal load, spatial uniformity of laser emission. Slope efficiency values as high as 58% in Quasi-CW pumping conditions and 54% in CW conditions was measured in two-layers structures. The production process and the number of layers influenced the behavior of the samples, in particular regarding the spatial uniformity of the laser emission. Samples made by tape casting have shown overall a better thermal stability with respect to the samples made by spray drying.

Titolo Convegno:

Parole chiavi: Ceramic materials; Defect density; Efficiency; Finite element method; Lasers; Multilayers; Optical multilayers; Optical properties; Pumping (laser); Slope stability; Solid state devices; Spray drying; Structural design; Thermal conductivity; Thermal effects; Ytterbium, Different structure; Multilayer ceramics; Spectroscopic property; Spray-dried powders; Surface deformation; Thermally induced stress; Transparent ceramic; Yb laser, Solid state lasers

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