Growth and spectroscopic properties of Tb3+-doped Na3La9O3(BO3)8 crystal

Tb3+ doped Na3La9O3(BO3)8 (Tb:NLBO) crystals have been grown by the top-seeded solution growth (TSSG) method. X-ray powder diffraction results show that the introduction of Tb3+ does not change the structure of NLBO crystal. Tb3+ concentration was determined by inductively coupled plasma optical emission spectrometry to be 1.089×1021 ions/cm3. The absorption and emission spectra were measured at room temperature by using a (1 0 0) oriented crystal wafer. According to the Judd-Ofelt theory, the spontaneous transition probabilities, fluorescence branch ratio, and the radiation lifetime of 5D4 state were calculated. The unpolarized and polarized emission properties under the 367 nm excitation were evaluated. The decay time of the 543 nm emission assigned to the 5D4-7F5 transition was also measured. All the results show that Tb:NLBO crystal would be a promising green laser material.