Effective 1.9 ~ 2.1 µm laser emissions in Er3+/Ho3+: GGG and Er3+/ Tm3+: GGG crystals sensitized with Er3+

Abstract

In this work, we report the enhanced 2080 nm emission from Ho3+ and 1999 nm emission of Tm3+ both via Er3+ sensitization in Gd3Ga5O12 (abbr. as GGG) crystals excited with 965 nm laser diode (LD) respectively. The underlying mechanisms were analyzed based on the measurements of absorption and emission spectra as well as fluorescence decay curves. Optical parameters including absorption and emission cross-sections, as well as fluorescence decay times are evaluated and compared. Owing to the co-doped sensitizer ion Er3+, a strong absorption near 965 nm plays an important role in the enhanced 2080 nm emission by transferring pump energy to Ho3+: 5I7 level in Er, Ho: GGG crystal, similarly, transferring energy from Er3+ to Tm3+: 3F4 level is conducive to improve 1999 nm emission in Er, Tm: GGG crystal. The above results demonstrate that the introduction of Er3+ into Ho3+ or Tm3+ activated materials offers a promising approach to obtain an enhanced 1.9–2.1 μm laser, which could operate upon 965 nm LD pumping, and the efficient energy transfer plays a key role in rare-earth ions doped luminescent materials.