Spectral analyses of Dy3+/Sr2+: LaF3 and Dy3+/Ca2+: LaF3 mixed crystals for laser applications.

Mixed crystals of Dy3+/Sr2+: LaF3 and Dy3+/Ca2+: LaF3 were grown by Bridgman technique and their spectral properties were investigated. Spectra broadening and peak shifts were observed, indicating the co-doping of Sr2+/Ca2+ brings about a more disordered local symmetry of Dy3+, which makes both crystals favorable for tunable lasing action. Low-temperature high resolution excitation and emission spectra were carried out for exploring the types of luminescent center of Dy3+ in crystals. Room-temperature absorption and emission spectra, together with the fluorescence decay curves were studied in both crystals for estimating their potentials for yellow and MIR lasers. Under 450 nm excitation, the largest emission cross-sections at 571 nm of 1.51 × 10-21 cm2 for Dy3+/Sr2+: LaF3 crystal and 1.56 × 10-21 cm2 for Dy3+/Ca2+: LaF3 crystal, along with the lifetimes of Dy3+: 4F9/2 level as 0.983 ms for Dy3+/Sr2+: LaF3 crystal, 1.143 ms for Dy3+/Ca2+: LaF3 crystal were obtained, respectively. Besides yellow emissions, MIR emissions approximately at 3 μm are more appealing. Under 1280 nm excitation, the largest emission cross-sections of 0.304 × 10-20 cm2 at 2885 nm in Dy3+/Sr2+: LaF3 crystal, and 0.319 × 10-20 cm2 at 2880 nm in Dy3+/Ca2+: LaF3 crystal, together with rather long lifetimes of Dy3+: 6H13/2 in the level of milliseconds were achieved, making them useful media for MIR lasers.