Enhanced 1.53 μm emission of Er3+ ions in phosphate glass via energy transfer from Cu+ ions

Optimizing the efficiency of Er3+ emission in the near-infrared telecommunication window in glass matrices is currently a subject of great interest in photonics research. In this work, Cu+ ions are shown to be successfully stabilized at a high concentration in Er-containing phosphate glass by a single-step melt-quench method, and demonstrated to transfer energy to Er3+ thereby enhancing the near-infrared emission about 15 times. The spectroscopic data indicate an energy conversion process where Cu+ ions first absorb photons broadly around 360 nm and subsequently transfer energy from the Stokes-shifted emitting states to resonant Er3+ absorption transitions in the visible. Consequently, the Er3+ electronic excited states decay and the 4I3/2 metastable state is populated, leading to the enhanced emission at 1.53  μ m. Monovalent copper ions are thus recognized as sensitizers of Er3+ ions, suggesting the potential of Cu+ co-doping for applications in the telecommunications, solar cells, and solid-state lasing realizable under broad band near-ultraviolet optical pumping.