Effects of Er3+ concentration on the optical properties of Er3+:SrGdGa3O7 single crystals

High-quality single crystals of different Er3+ concentration doped SrGdGa3O7(SGGO) were grown successfully by the Czochralski method. The absorption, up-conversion, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er:4I13/2 and 4I11/2 levels in Er:SGGO crystal were measured at room temperature. As the concentration of Er3+ ions increase, the spectra of Er:SGGO crystals show weaker near-infrared emission and stronger mid-infrared emission. The lifetime of the 4I13/2 state decreases by nearly 7times while the lifetime of the 4I11/2 state decreases by only about 1.3 times in the Er:SGGO crystals. These results indicate that the heavily Er3+ doped SGGO crystals is beneficial to improve the 2.7 μm laser.