METHOD FOR MANUFACTURING A RARE EARTH DOPED OPTICAL WAVEGUIDE, AND A RARE EARTH DOPED OPTICAL WAVEGUIDE

The present application concerns a method for manufacturing an aluminium oxide optical waveguide doped with rare earth ions. The present application further concerns an aluminium oxide optical waveguide doped with rare earth ions that are preferably manufactured by said method. According to the present invention, the method comprises providing a substrate, depositing an aluminium oxide waveguide core layer doped with ions of a rare earth metal onto the substrate, and arranging a cladding layer on the deposited waveguide core, said arranging comprising at least one processing step during which the deposited waveguide core is subjected to a given maximum temperature. The method is characterized in that depositing the waveguide core comprises forming nano-crystallites in the waveguide core. A lowest temperature at which a quenching percentage of the deposited waveguide core significantly increases, exceeds the given maximum temperature, wherein the given maximum temperature is about 400 degrees Celsius or higher.