Spectroscopic characteristics of 1.54 μm emission in Er/Yb:LiNbO3 crystals tridoped with In3+ ions

Highlights: ► Zr/Er/Yb:LiNbO3 crystals were grown by Czochralski technique. ► The strongest 1.54 μm emission is observed for In (2 mol%)-doped Er/Yb:LiNbO3. ► Judd–Ofelt parameters based on UV–vis–infrared absorption spectra are discussed. ► Absorption/emission cross-section and fluorescence lifetimes are reported. ► Gain cross-section spectra in the eye-safe regime of 1450–1650 nm are studied. - Abstract: A series of Er/Yb:LiNbO3 crystals tridoped with x mol% In3+ ions (x = 1, 2 and 3 mol%) was grown by Czochralski technique. Under 980 nm excitation, the strongest intensity of 1.54 μm emission was observed for 2 mol% In3+-tridoped Er/Yb:LiNbO3 crystal. The UV–vis–infrared absorption spectra of In/Er/Yb:LiNbO3 crystals were measured, and Judd–Ofelt (J–O) theory was carried out to predict the J–O intensity parameters (Ωt), radiative lifetime τrad and fluorescence branching ratio β. The emission cross-section of the 4I13/2 → 4I15/2 transition of Er3+ ion was calculated by Füchtbauer–Ladenburg (F-L) method. The gain cross-section, estimated as a function of the population inversion ratio, allowed us to evaluate a potential laser performance of In/Er/Yb:LiNbO3 crystal at 1.54 μm emission. The fluorescence lifetimes of the 4I13/2 → 4I15/2 transition in In/Er/Yb:LiNbO3 crystals were measured.