This paper presents the results of a study of the structural, optical, and photoluminescence properties of a thin layer of oxidized nanoporous silicon doped with erbium ions. Structural studies have shown that silicon nanoclusters of spherical shape with dimensions from 5 to 35 nm are present in the layer. The transmittance of a layer of oxidized nanoporous silicon doped with erbium ions in the wavelength region from 1.2 to 2.0 μm was at least 54%, and this makes it possible to use it to create active planar waveguides that can be used in integrated optical structures of silicon photonics. Investigation of the photoluminescence spectra at temperatures of 100 and 300 K showed the presence of peaks that characterize the luminescence of erbium ions.