Spectroscopic investigation of the influence of Cu+ ions and plasmonic Cu particles on Ho3+ luminescence in phosphate glass

Abstract

Abstract The luminescence of Ho3+ ions in phosphate glass containing a high concentration of Cu+ ions and also Cu nanoparticles (NPs) is reported. The glasses consisting of a barium-phosphate matrix were obtained by thermal processing and characterized by Fourier transform-infrared spectroscopy (FT-IR), optical absorption, and photoluminescence (PL) spectroscopy. The FT-IR data appeared consistent with a network modifier role of Cu+ ions with no significant structural alteration induced by NPs. The absorption spectrum for heat-treated Cu+/Ho3+ co-doped glass exhibited narrow plasmon resonance for Cu NPs around 575 nm. It was indicated that Cu+ PL dominates for excitation resonant with Cu+ absorption. Conversely, Ho3+ emission is clearly displayed for excitation in the visible (e.g. 450 nm) away from Cu+ excitation. Precipitating Cu NPs resulted in suppression of Cu+ band emission and the Ho3+ PL being quenched. Following the assessment of Ho3+ emission dynamics, likely energy transfer processes involving Cu NPs as energy acceptors were proposed.