Locally Er-Doped Near-Stoichiometric LiNbO₃ Crystal for Integrated Optics

X- and Z-cut locally Er-doped near-stoichiometric LiNbO 3 crystals have been fabricated using two methods: direct vapor transport equilibration (VTE) treatment on congruent crystals coated with erbium (Er) metal, and a two-step process with standard thermal in-diffusion of Er metal followed by VTE treatment. Detailed studies on the crystalline phase, the Li composition, the diffusivity and the spectroscopic property of Er 3+ ion, and the diffused surface roughness indicate that there is a limitation on the initial Er metal film thickness, and the near-stoichiometric Er:LiNbO 3 crystals prepared by both methods are promising substrates for integrated optics applications.