Enhanced 2.7 μm emission and its origin in Nd3+/Er3+ codoped SrGdGa3O7 crystal

Abstract

Nd3+ sensitized Er3+:4I11/2→4I13/2 mid-infrared (MIR) emission around 2.7μm was achieved in SrGdGa3O7 single crystal for the first time. The effect of Nd3+ on the absorption, near-infrared (NIR) and MIR fluorescence properties of Er3+ ions were investigated. It is found that Nd3+ greatly improves the absorption pump efficiency and thus enhances the Er3+~2.7μm emission by nearly 10 times under 808nm laser diode (LD) excitation, at the same time quenches the ~1.5μm near-infrared emission of the lower level Er3+:4I13/2 and thus suppresses the self-saturation problem effectively. The luminescent mechanism for the Nd3+/Er3+:SrGdGa3O7 crystal was analyzed and the possible energy transfer processes were proposed. The energy transfer efficiencies of Nd:4F3/2→Er:4I11/2 and Er:4I13/2→Nd:4I15/2 are estimated to be 85.8% and close to 100%, respectively. The results indicate that the introduction of Nd3+ is very beneficial in achieving 2.7μm laser in Er3+:SrGdGa3O7 crystal which could act as a potential gain media for LD pumped MIR laser.