Enhanced 3.9 µm emission from diode pumped Ho3+/Eu3+ codoped fluoroindate glasses

The use of E u 3+ codoping for enhancing the H o 3+ : 5 I 5 → 5 I 6 emission in fluoroindate glasses shows tha E u 3+ could depopulate the lower laser state H o 3+ : 5 I 6 while having little effect on the upper state H o 3+ : 5 I 5 , resulting in greater population inversion. The H o 3+ / E u 3+ codoped glass has high spontaneous transition probability (6.31 s -1 ) together with large emission cross section (7.68×10 -21 c m 2 ). This study indicates that codoping of H o 3+ with E u 3+ is a feasible alternative to quench the lower energy level of the 3.9 µm emission and the H o 3+ / E u 3+ codoped fluoroindate glass is a promising material for efficient 3.9 µm fiber lasers.