Spectroscopic properties of Er:La _0.5 Gd _1.5 Si ₂ O ₇ crystal with broad 1.5-1.6 μ 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.