Spectroscopic properties of Er:La_0.5Gd_1.5Si₂O₇ crystal with broad 1.5-1.6 <b>μ</b>m gain band

An Er 3+ doped La 0.5 Gd 1.5 Si 2 O 7 crystal was grown by the Czochralski method. The crystal possesses an average Vickers hardness of 750 H V and a refractive index of about 1.752 at 1.5-1.6 μm. The spontaneous emission probabilities, branching ratio, and radiative lifetime were calculated based on the Judd-Ofelt theory. The emission cross section at peak fluorescence wavelength of 1535 nm of the crystal is 0.45 × 10 −20 cm 2 , and the full width at half-maximum of the 1.5-1.6 μm gain band at an inversion parameter of 0.5 is 84 nm. The fluorescence lifetimes of the 4 I 13/2 and 4 I 11/2 multiplets of Er 3+ in the crystal are 5.0 ms and 11.8 μs, respectively. The results indicate that the Er:La 0.5 Gd 1.5 Si 2 O 7 crystal may be a potential gain medium for the tunable and ultrashort pulse lasers at 1.5-1.6 μm.