Near-UV sensitized 1.06 μm emission of Nd³⁺ ions via monovalent copper in phosphate glass

Abstract Monovalent copper ions effectively incorporated in Nd-containing phosphate glass by a single-step melt-quench method have been established as near-ultraviolet (UV) sensitizers of Nd³⁺ ions, resulting in a remarkable ⁴F_3/2 → ⁴I_11/2 emission at 1.06 μm. The spectroscopic data indicates an efficient energy conversion process. The Cu⁺ ions first absorb photons broadly around 360 nm, and subsequently transfer the energy from the Stokes-shifted emitting states to resonant Nd³⁺ energy levels in the visible. Ultimately, the Nd³⁺ electronic excited states decay and the upper lasing state ⁴F_3/2 is populated, leading to the enhanced emission at 1.06 μm. The characteristic features of the Cu⁺ visible emission spectra and the reduced lifetime of the corresponding Cu⁺ donor states indicate an efficient non-radiative transfer. The Cu⁺/Nd³⁺ co-doped phosphate glass appears suitable as solid-state laser material with enhanced pump range in the near-UV part of the spectrum and for solar spectral conversion in photovoltaic cells.