Absorption and emission properties of Eu3+ doped Cs2Bi2O(Ge2O7) acentric biaxial single crystal

Optical properties of cesium bismuth germanate Cs2Bi2O(Ge2O7) (CBGO) nonlinear single crystal doped with trivalent europium (Eu3+) ions grown from melt were investigated. Strong Eu3+ emission lines in the orange-red range centered at 576, 596, and 617 nm originating from the 5D0 to 7F0,1,2 transitions, respectively, were observed. Judd-Ofelt intensity parameters describing f-f transitions were calculated from the room temperature emission and excitation spectra and were used to determine spectroscopic parameters such as radiative lifetimes, transition probabilities and branching ratios3 for 5D0 level of Eu3+. The values obtained by using Judd-Ofelt approach were compared with experimental results for the 5D0 excited state. The measurement of the 5D0 fluorescence decay of Eu3+ ions in the Cs2Bi2O(Ge2O7) matrix (0.5 at.% in the alloy) confirmed its exponential nature, with a time constant of 0.82 ms at 300 K. The high-resolution laser spectroscopy of CBGO Eu3+ performed at 10 K confirmed the Eu3+ distribution into two distinct sites. Based on both the results of optical spectroscopy and structural analysis, the allocation of sites for Eu3+ ions was discussed. •Cs2Bi2O(Ge2O7):Eu3+ crystals have been grown from stoichiometric melts under conditions of low temperature gradient.•Judd-Ofelt intensity parameters for f-f transitions in CGBO:Eu3+ have been determined.•The Eu3+ distribution into two distinct sites in CBGO host has been experimentally confirmed.•The values of transition probability and radiative lifetime of the 5D0 level of Eu3+ in CBGO crystal have been determined.