Waveguide amplifier fabrication method and waveguide amplifier

Photonic integrated circuit waveguide amplifier fabrication method comprising providing at least one support cladding material or layer supporting at least one silicon nitride material or layer and/or at least one embedding cladding material or layer comprising the at least one silicon nitride material or layer embedded inside the at least one embedding cladding material or layer; wherein the at least one silicon nitride material or layer (has a material or layer thickness that is less than or equal to 400nm and greater than or equal to 40nm; and carrying out rare-earth ion implantation, at rare-earth ion acceleration values between 0.01 mev and 0.5 mev, by ion irradiation of at least one surface of the at least one supported and/or embedded silicon nitride material or layer, the at least one rare-earth ion implanted silicon nitride material or layer defining a waveguide core of the waveguide amplifier.