Fluoroindate Glass Co-Doped with Yb³⁺/Ho³⁺ as a 2.85 μm Luminescent Source for MID-IR Sensing

This work reports on the fabrication and analysis of near-infrared and mid-infrared luminescence spectra and their decays in fluoroindate glasses co-doped with Yb³⁺/Ho³⁺. The attention has been paid to the analysis of the Yb³⁺→ Ho³⁺ energy transfer processed ions in fluoroindate glasses pumped by 976 nm laser diode. The most effective sensitization for 2 μm luminescence has been obtained in glass co-doped with 0.8YbF₃/1.6HoF₃. Further study in the mid-infrared spectral range (2.85 μm) showed that the maximum emission intensity has been obtained in fluoroindate glass co-doped with 0.1YbF₃/1.4HoF₃. The obtained efficiency of Yb³⁺→ Ho³⁺ energy transfer was calculated to be up to 61% (0.8YbF₃/1.6HoF₃), which confirms the possibility of obtaining an efficient glass or glass fiber infrared source for a MID-infrared (MID-IR) sensing application.