High-temperature diffusion doping of thin-film lithium niobate

Surface-doping of lithium niobate wafers with rare earth or optically damage-resistant ions by physical vapour deposition and high-temperature in-diffusion is a cost-efficient and flexible method for the fabrication of thin-film LN or LNOI with dopants which are not common in crystal growth. LNOI doped with Er, Yb, Tm, Pr, Zn and Zr have been fabricated with different concentrations. As an example, the fluorescence spectra of Er:Yb:LNOI samples were recorded, and a small-signal net gain of 3.7 dB/cm was measured in ridge waveguides.