Spectral properties of Ho3+/Tm3+ co-doped β′-Gd2(MoO4)3 crystal as laser gain medium around 2.0 μm

• Polarized spectral properties of Ho3+/Tm3+:β′-Gd2(MoO4)3 crystal were studied.
• Broad absorption band of the crystal around 795 nm is suitable for LD pumping.
• Peak emission cross section around 2.0 μm is comparable to that of Ho3+:YAG.
• Coupling decay behavior of Tm3+ and Ho3+ embodies energy transfer between them.
• Ho3+ laser around 2.0 μm with a tunable range of about 130 nm can be expected.

Ho3+/Tm3+ co-doped β′-Gd2(MoO4)3 single crystal was investigated as gain medium for Ho3+ laser around 2.0 μm. Polarized absorption and fluorescence spectra of the crystal were measured. Polarized spectral parameters of Ho3+ ions in the crystal were calculated and the gain curves around 2.0 μm were estimated. The fluorescence decay curves for Tm3+ and Ho3+ ions related to the 2.0 μm laser were measured and analyzed. The distinct coupled decay behavior for the Ho3+/Tm3+ co-doped system embodies the existence of energy transfer between Tm3+ and Ho3+ ions.