Low-threshold, highly efficient Gd3+, Lu3+ co-doped KY(WO4)2:Yb3+ planar waveguide lasers

• Published in: Laser physics letters 2009-10, Vol.6 (11), p.800-805
• Main Authors: Geskus, D., Aravazhi, S., Bernhardi, E., Grivas, C., Harkema, S., Hametner, K., Günther, D., Wörhoff, K., Pollnau, M.
• Format: Article
• Language: English
• Subjects: Continuous operation; CW laser; dielectric waveguides; double tungstates; epitaxial layers; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Laser optical systems: design and operation; liquid phase epitaxy; Optical elements, devices, and systems; optical planar waveguide; Optical waveguides and coupleurs; Optics; Physics; waveguide laser; ytterbium doping; ytterbium doping; optical planar waveguide; dielectric waveguides; waveguide laser; CW laser; liquid phase epitaxy; double tungstates; epitaxial layers
• ISSN: 1612-2011; 1612-202X
• DOI: 10.1002/lapl.200910084

High‐quality crystalline KY(WO4)2:Yb3+ layers codoped with large concentrations of optically inert Gd3+ and Lu3+ ions were grown by liquid phase epitaxy. Continuous‐wave laser operation in a planar waveguide configuration was observed at 1025 nm. For 23% output coupling, a maximum output power of 195 mW was obtained; a slope efficiency of 82.3% was derived, which to the best of our knowledge is the highest value yet reported for a planar waveguide laser to date. For 1.7% output coupling, a laser threshold as low as 18 mW of absorbed pump power was achieved, which is largely due to the enhanced refractive index contrast of ∼7.5 × 10–3 between the active layer and the undoped KY(WO4)2 substrate attained by the co‐doping, leading to well‐confined pump and laser modes. (© 2009 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA)