Scattering-promoted plasmonic enhancement of Eu³⁺ ions photoluminescence in dichroic Cu nanocomposite glass

The red emission of Eu³⁺ ions embedded in glasses containing copper with distinct plasmonic properties is reported. Either a photoluminescence (PL) enhancement or quenching is manifested depending on whether the nanocomposite is dichroic (scatters red but transmits blue) or not (ruby-colored). In addition, Eu³⁺ emission in the dichroic glass is indicated to be either enhanced or quenched depending on the excitation wavelength. The glasses consisting of barium–phosphate matrix co-doped with Cu and Eu were obtained by thermal processing. Characterizations were then performed by Fourier transform-infrared spectroscopy, UV/Vis optical absorption, PL spectroscopy with decay dynamics assessment, and light scattering measurements. The latter were conducted for the first time on plasmonic metal nanocomposite glasses, aiming to clarify the origin of the distinct optical properties. It is supported that favorable conditions for the PL enhancement are achieved when the emission of Eu³⁺ ions can benefit from light scattering by plasmonic Cu particles. However, an excitation energy transfer from Eu³⁺ to Cu nanoparticles via interband transitions leading to the PL quenching should be minimized.