Investigation of Pr³⁺ Near-Infrared Emission in Plasmonic and Dichroic Copper Nanocomposite Glasses

Melt-quenched Pr³⁺-doped phosphate glass containing Cu⁺ and Sn²⁺ as redox couple to induce Cu nanoparticle (NP) precipitation was subjected to heat treatment to develop nanocomposite glasses with plasmonic and dichroic character. The purpose was to examine the impact of Cu NPs producing dichroism on the near-infrared (NIR) emission from Pr³⁺. The parent and isothermally heat-treated glasses (520 °C: 20, 40, 60 min) were characterized by differential scanning calorimetry, Fourier transform-infrared spectroscopy, optical extinction, and photoluminescence spectroscopy with decay dynamics. From the samples, the heat-treated for 40 and 60 min showed broad plasmonic bands alongside dichroism wherein the glasses scatter red light but transmit blue. The Pr³⁺ NIR emission encompassing ¹D₂ → ³F₄, ³F₃,¹G₄ transitions was evaluated under 445 and 590 nm excitation. An increased emission was not exhibited, whereas a quenching effect became evident for samples heat-treated for 40 and 60 min. Different interactions involving Pr³⁺ ions and Cu NPs are discussed.