Spectroscopic properties and Judd-Ofelt analysis of Nd doped GdVO4 single crystals grown by OFZ method

GdVO4 single crystals doped with different concentration of Nd (0.6, 0.8, 1.0 and 1.2 at.%) were grown by optical floating zone method. The absorption coefficient measured for two orthogonal polarization of light is different due to anisotropic structure in both the direction. The line strength and Judd-Ofelt parameters evaluated from the recorded absorption spectra are also dependent on the polarization of the incident light. Further, the spectroscopic quality factor was estimated by Judd Ofelt parameters and found to be maximum for 0.8 at.% Nd doped GdVO4 crystals. The emission study shows that photoluminescence (PL) intensity at 1062 (lasing wavelength), 1069 and 1081 nm increases with the doping concentration of Nd up to 0.8 at.% and beyond that the PL intensity at all emission wavelengths decreases. The emission cross-section with excitation at 808 nm was estimated by Judd Ofelt theory for the F-4(3/2) -> (4)l(11/2) transition and it was found to be independent of doping of Nd in GdVO4. The measured fluorescence life-time of Nd:GdVO4 samples is similar to 100, 101, 92 and 93 is corresponding to the doping concentration of 0.6, 0.8, 1.0 and 1.2 at.% of Nd respectively. The measured fluorescence life-time exhibits the maximum value for 0.8 at.% of Nd doping. The decrease in the PL intensity as well as fluorescence life-time for higher doping concentration is because of quenching due to ion-to-ion interaction in the crystal. All the spectroscopic investigation presented here suggest that the optimum concentration of Nd ion in GdV4 single crystals is 0.8 at.%, at which the best lasing performance can be obtained.