Fs-laser-written erbium-doped double tungstate waveguide laser

We report on the first erbium (Er3+) doped double tungstate waveguide laser. As a gain material, we studied a monoclinic Er3+:KLu(WO4)(2) crystal. A depressed-index buried channel waveguide formed by a 60 mu m-diameter circular cladding was fabricated by 3D femtosecond direct laser writing. The waveguide was characterized by confocal laser microscopy, mu-Raman and mu-luminescence mapping, confirming that the crystallinity of the core is preserved. The waveguide laser, diode pumped at 981 nm, generated 8.9 mW at 1533.6 nm with a slope efficiency of 20.9% in the continuous-wave regime. The laser polarization was linear (E vertical bar vertical bar N-m). The laser threshold was at 93 mW of absorbed pump power. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement