Enhanced 3.9  µm emission from diode pumpedHo3+/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 that 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.