Low propagation losses of an Er:Y2O3 planar waveguide grown by alternate-target pulsed laser deposition

We report on waveguiding properties in epitaxial ${\mathrm{Er:Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ films grown by pulsed-laser deposition on sapphire [0001] substrate. Characterization of the as-grown films by x-ray diffraction, atomic force microscopy, and Rutherford backscattering revealed that the films were highly crystalline and textured along the [111] direction and possessed an average surface roughness of 2 nm for a 0.69-μm-thick film. The investigation of the emission spectra confirms the proper structural position for the ${\mathrm{Er}}^{\mathrm{3+}}$ ions in the ${\mathrm{Y}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ matrix and that the films guide optical waves along the entire length (5 mm) of the film yielding a propagation loss of $\text{<1\hspace{0.05em}}\mathrm{dB/cm}$ at 800 nm.