Epitaxial layers of KY1−x−yGdxLuy(WO4)2 doped with Er3+ and Tm3+ for planar waveguide lasers

Here we show the results we obtained in the fabrication of planar waveguide lasers based on monoclinic double tungstates doped with Er3+ and Tm3+. We have successfully introduced these ions into the lattice matched KY0.59Gd0.19Lu0.22(WO4)2 epitaxial layers grown on KY(WO4)2 substrates without loss of optical quality and keeping a high refractive index contrast between the epitaxial layer and the substrate. We characterized the waveguiding properties of these epitaxial layers at λ = 632.8 nm by dark modes spectroscopy, and we showed that these waveguides can support several TE and TM modes. Spectroscopic characterization of the active lanthanide ions in these crystals is also presented.