Optical spectroscopy of Tm3+ in a locally disordered Li2Gd4(MoO4)7 crystal: A candidate for tunable and ultrafast pulse lasers

The optical properties of a locally disordered Tm3+:Li2Gd4(MoO4)7 crystal have been investigated extensively to assess its feasibility of efficient ultrafast laser operation in the 2 μm spectral region. The main spectroscopic parameters relevant to laser applications have been evaluated by analyzing the polarized absorption spectra using the Judd–Ofelt theory. The cross-relaxation mechanisms between Tm3+ levels have been applied to analyze the lifetimes of the 3F4, 3H4, and 1G4 manifolds. The potential for producing subpicosecond laser pulses has been discussed on the basis of the calculated emission and gain cross-sections around 2 μm wavelength. The crystal exhibits broad optical bandwidths, large absorption/emission cross sections, and a long 3F4 fluorescence lifetime. All these features indicate that the Tm3+:Li2Gd4(MoO4)7 crystal is a promising gain medium for tunable and ultrafast (fs) pulse lasers.

► Detailed spectral properties of the Tm3+:Li2Gd4(MoO4)7 crystal have been investigated.
► The crystal exhibits favorably large cross-sections and broad optical bandwidths.
► The spectral parameters is similar to those of the Tm3+:Li0.375Lu0.375Ba0.25MoO4 crystal.
► The crystal shows the potential of generation of subpicosecond laser pulses.