Curved Yb:YAG waveguide lasers, fabricated by femtosecond laser inscription.

Straight and s-curve Yb(7%):YAG waveguides have been fabricated with the femtosecond laser writing technique. By employing a novel writing scheme an increase of the refractive index change could be achieved in comparison to waveguides written with the standard procedure. Straight waveguides, fabricated with this scheme, enabled highly efficient Ti:sapphire laser pumped waveguide lasers with slope efficiencies of 79% and output powers of more than 1 W. With slope efficiencies from 50% to 60% for the curved waveguide lasers with radii of curvature of R ≥ 20 mm the possibility of fs-laser written complex optical devices is demonstrated.