Near-infrared quantum cutting in OH^- free Nd³⁺- Yb³⁺ co-doped low-silica calcium aluminosilicate glasses

Near-infrared (NIR) quantum cutting (QC) through downconversion (DC) in OH^- free Nd³⁺-Yb³⁺ co-doped low-silica calcium aluminosilicate glasses (LSCAS) was observed. Luminescence and time-resolved measurements allowed the investigation of the origin of the Yb³⁺ DC emission. Our results showed that only one NIR photon is emitted by the Yb ³⁺ ion through one-step energy transfer after excitation with a VIS photon absorbed by the Nd³⁺ ion. However, after excitation with an UV photon absorbed by the Nd³⁺ ion, two NIR photons are emitted by the Yb³⁺ ion through two-step energy transfer. The Yb³⁺ DC normalized intensities after excitation at 325 nm showed an increase of a factor of two compared to that of 514 nm excitation. In addition, the energy transfer probabilities from Nd³⁺ to Yb³⁺ were estimated by analyzing the Yb³⁺ DC kinetics. The overall results showed an efficient QC through DC process in Nd³⁺-Yb³⁺ co-doped LSCAS glasses, and the energy transfer mechanisms are discussed.