Preparation and luminescence properties of Yb3+ activated Gd2GeO5

► Structure of Yb:Gd2GeO5 was refined. ► Its photoluminescence spectrum is one of the known broader emission of Yb3+. ► Crystal field parameters Bqk and energy levels were calculated, respectively. ► The energy splitting of ground state is up to 1065 cm-1. Polycrystalline Yb:Gd2GeO5 was prepared by solid state reaction method, and its structure, spectral properties, and energy structure were studied. The Yb:Gd2GeO5 belongs to space group P21/c, and its photoluminescence spectrum includes the range from 975 to 1088nm which is one of the known broader emission of Yb3+. The broad emission spectrum is necessary for ultrashort laser operation and laser tuning. Crystal field parameters Bqk and energy levels of Yb3+ at two symmetry sites in Gd2GeO5 were calculated by the simple overlap model, respectively. The calculated energy levels are consistent with the experimental very well. The energy splitting of Yb3+2F7/2 ground state in Gd2GeO5 is up to 1065cm−1. According to Boltzmann distribution, the thermal population ratio of the highest terminal laser level is about 0.605% and less than 2.32% of YAG by one order, which is very beneficial to population inversion. All results indicate that Yb:Gd2GeO5 may be a promising laser crystal material for ultrashort and tunable all-solid laser.