Broadened effect of Dy around 3 μm of Yb/Er/Dy: PbF₂ crystal for broadband tunable lasers

Abstract

It is well known that the laser crystal with mid‐infrared (MIR) broadened and enhanced luminescence is of great significance for various applications, such as atmospheric monitoring, medical surgery and compact, and efficient coherent sources. Herein, we exploit the sensitization and deactivation effects of Yb3+/Dy3+ ions to achieve broadening and enhancement ~3 μm emission of Er3+: 4I11/2→4I13/2 transition in Yb3+/Er3+/Dy3+: PbF2 crystal. The energy transfer (ET) mechanism between Yb3+, Er3+, and Dy3+ was studied. A broadened and enhanced emission with a full width at half maximum of 265 nm was obtained at ~3 μm due to the fact that Er3+ and Dy3+ ions were used as the emission center at the same time. On the one hand, the incorporation of Dy3+ ion can solve the self‐termination bottleneck effect of Er3+ ion, reducing the lifetime of Er3+: 4I13/2 level. On the other hand, Dy3+ ion can simultaneously serve as the emission center of 3 μm, broadening and enhancing the emission of 3 μm. The experiments show that the corresponding ET efficiency Er3+: 4I13/2→Dy3+: 6H11/2 level is as high as 98.0%, indicating that Dy3+ ion can be used as an effective deactivating ion, benefitting to achieve broadening and enhancing MIR emission around 3 μm. Hence, the Yb3+/Er3+/Dy3+: PbF2 crystal is an attractive laser medium for MIR broadband tunable laser applications.