Effect of Er3+ concentration on spectral characteristic and 2.79 μm laser performance of Er:YSGG crystal

Er3+-doped YSGG crystals with nine different concentrations were grown successfully by Czochralski (Cz) method. The absorption, emission spectra, and the fluorescence decay curves are investigated comparably. Based on Judd–Ofelt (J–O) theory, the J–O intensity parameters Ωt (t = 2, 4, 6), the experimental and theoretical oscillator strengths are calculated with the absorption spectra. The results show that the 1 at. % lowly Er3+-doped YSGG crystal is more properly used in up-conversion laser applications and 5 at. % Er:YSGG crystal is a better candidate for 1.5 μm lasers within these nine crystals, while the heavily Er3+-doped YSGG crystal is beneficial for the 2.7 μm laser output. But if the doping concentration goes too high, the up-conversion rate of the 4I11/2 level could be higher than that of the 4I13/2 level, which would lead to increasing the up-conversion emission and quenching the mid-infrared emission. The 2.79 μm laser performance of LD end-pumped 40 at. % Er:YSGG crystal is also demonstrated. •Er:YSGG crystals with nine different concentrations were grown by Cz method.•The luminescence properties of Er3+ in YSGG crystals are fully researched.•1 at. % Er:YSGG crystal is more suitable for up-conversion laser applications.•5 at. % Er:YSGG crystal is a better candidate for 1.5 μm lasers.•A maximum power of 409 mW is obtained at LD end-pumped 40 at. % Er:YSGG.