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

- Enhanced 2.7 μm emission of Er3+ via Nd3+ sensitization was obtained in SrGdGa3O7 crystal for the first time.
- The detailed spectroscopy of Nd,Er:SrGdGa3O7 crystal were discussed.
- The energy transfer mechanism was analyzed and energy transfer efficiencies between Nd3+/Er3+ were evaluated.
- Nd,Er:SrGdGa3O7 crystal is proved to be a potential 2.7 μm laser gain media under 808 nm LD excitation.

Nd3+ sensitized Er3+:4I11/2→4I13/2 mid-infrared (MIR) emission around 2.7 μm 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+~2.7 μm emission by nearly 10 times under 808 nm laser diode (LD) excitation, at the same time quenches the ~1.5 μm 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 2.7 μm laser in Er3+:SrGdGa3O7 crystal which could act as a potential gain media for LD pumped MIR laser.