Spectroscopic properties of Sm3+ impurity in YAl3(BO3)4 single crystal

Single crystal of YAl3(BO3)4 (YAB) containing 1 at.% of Sm3+ was grown by the top seeded high temperature solution method. Optical absorption, excitation and luminescence spectra as well as luminescence decay curves were recorded for this system at 10 K and at room temperature. Crystal field splitting of Sm3+ multiplets involved in absorption and emission transitions was derived from low temperature optical spectra and used to interpret peculiarities of emission bands. Careful analysis of low temperature optical spectra points to the presence of one type of Sm3+ site in contrast to two non-equivalent sites reported for Yb3+:YAB system. It was found that among numerous radiative transitions originating in the single metastable 4G5/2 level of Sm3+ the 4G5/2-6H7/2 transition around 598 nm is particularly intense in YAB. The transition terminates on the excited multiplet well above the ground state and thereby is consistent with the four level laser operation scheme. The 4G5/2 luminescence was found to be long-lived with the lifetime value of 2 ms at room temperature indicating small contribution of non-radiative transitions to the 4G5/2 relaxation.