Erbium-Doped fluoride glass waveguides for laser applications

A compact green laser diode pumped rare earth laser source is interesting for a range of medical, spectroscopic and communications applications. Since such a device is not commercially available up to now we are working on the development of an erbium-doped fluoride glass up-conversion waveguide laser. The actual fabrication of fluoride glass, especially ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF), strip waveguides on monocrystalline CaF₂-substrates is described. The ZBLAN glass was doped with 3 mol% erbium fluoride (ErF₃). Hot dip spin coating was used for the coating of the substrates. Structuring of the glass films was done by photolithography and a wet chemical etching method. Improvement of these processes will be an important step for the realization of a low loss waveguide as well as the laser. Until now planar waveguides with thicknesses down to 30 μm were achieved. Parameters for laser activity were simulated and following that simulation a diode-pumped waveguide laser is feasible. A simple laser setup for the waveguide samples with external resonator mirrors was built.