Raman spectra and laser properties of Yb-doped yttrium orthovanadate crystals

Yb-doped yttrium orthovanadate YbxY1−xVO4 (YYV), with x=0.02, crystallizes with a zircon-type structure in the tetragonal system, conforming to the space group I41/amd. The lattice constants are a=0.7122(5) and c=0.6291(3) nm at room temperature. The primitive cell contains four formula units. The Raman spectra and crystallography show no distortion of the VO4 and Y/YbO8 groups. The crystal field is similar to that of the YVO4 crystal and is suitable for the dopant Yb3+ ions. A strong absorption at 975 nm arises from the F27/2 to F25/2 transition; with a bandwidth of 70 nm it may provide a useful pump band for InGaAs diode lasers. This band is about seven times broader than that of Nd-doped yttrium aluminum garnet and more than three times as broad as that of Nd-doped yttrium orthovanadate. The measured absorption of the YYV is compared to Judd–Ofelt (JO) theory. When applied, the JO theory of parity-forbidden electric-dipole transitions of rare earth ions on noncentrosymmetric sites demonstrates good agreement. The fluorescence spectrum reveals a ground state splitting of ΔE=463 cm−1. The fitted fluorescence lifetime is 1.18 ms at the wavelength of 1.0 μm. The calculated absorption cross section is 1.38×10−20 cm2. The order of magnitude of the emission cross section is estimated as 10−21 cm2. In Yb-doped yttrium aluminum garnet, the fluorescence lifetime is about 1.16–1.30 ms and the absorption cross section is 1.5×10−20 cm2. In Nd-doped yttrium orthovanadate, the fluorescence lifetime is 115 μs and the emission cross section is 10.7×10−19 cm2. A suitable concentration of the Yb3+ ions doped in the YbxY1−xVO4 crystals should modify the optical and the potential laser properties of the crystals.