Research on a novel molybdate Er3+:KBaY(MoO4)3 crystal as a prominent 1.55 μm laser medium

An Er3+:KBaY(MoO4)3 (denoted Er3+:KBYM) crystal with excellent optical quality was grown for the first time by the top-seeded-solution growth method (TSSG) from a flux of K2Mo2O7 and its morphology, including concentration of Er3+ ions was analyzed. The concentration of Er3+ ion and spectroscopic properties were measured and investigated. Applying the Judd-Ofelt theory, the spectroscopic parameters of Er3+:KBYM crystal, including the oscillator intensity parameters Ωt(t=2,4,6), spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes, were calculated and analyzed. The stimulated emission cross-sections at around 1.55 μm, corresponding to the 4I13/2 → 4I15/2 transition were 1.01 × 10−20 cm2, 1.32 × 10−20 cm2 and 1.10 × 10−20 cm2 for the X-, Y- and Z-polarizations, respectively. The fluorescence lifetime of the 4I13/2 state was measured and discussed. The fluorescence decay curve for the 4I13/2 state exhibited a single exponential behavior and fluorescence lifetime was fitted to be 5.35 ms. Two intense green up-conversion fluorescence bands located at 533 nm and 554 nm and a broadened weak red fluorescence at 665 nm were observed at 984 nm excitation, and the energy transfer mechanism was discussed.