Optical wave propagation in epitaxial Nd:Y₂O₃ planar waveguides, W. Li, S. E. Webster, R. Kumaran, S. Penson, T. Tiedje, Appl. Optics, 49, 586-591 (2010)

Optical wave propagation in neodymium-doped yttrium oxide (Nd:Y₂O₃) films grown on R-plane sapphire substrates by molecular beam epitaxy has been studied by the prism coupler method. The measurements yield propagation loss data, the refractive index, and the dispersion relation. The refractive index of the Nd:Y₂O₃ at 632.8 nm is found to be 1.909, and the lowest propagation loss measured is 0.9+/-0.2 cm-1 at 1046 nm with a polymethyl methacrylate top cladding layer on a film with 6 nm root mean square surface roughness. The loss measurements suggest that the majority loss of this planar waveguide sample is scatter from surface roughness that can be described by the model of Payne and Lacey