Spectroscopic investigation of 2.0 µm emission in Ho3+-doped fluoroindate glasses

In this paper we report the optical characterization of Ho 3+ -doped fluoroindate glasses with the following composition (40 − x )InF 3 –20SrF 2 –16BaF 2 –20ZnF 2 –2GdF 3 –2NaF– x HoF 3 with x = 1.0, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0 and 9.0 mol%. This investigation was done by means of absorption, fluorescence and lifetime measurements. The phenomenological intensity parameters Ω λ (λ = 2, 4, 6) were calculated using the standard Judd–Ofelt theory. In order to evaluate potential applications of the 5 I 7 → 5 I 8 Ho 3+ emission at 2.0 µm, the radiative lifetime, total transition rate and emission cross section were determined. The effect of Ho 3+ concentration on the fluorescence intensity and lifetimes was analysed. It was concluded that the non-radiative losses of the 5 I 7 level are mainly due to energy migration among Ho 3+ ions followed by energy transfer to quenching impurities.