Growth and optical investigation of Nd co-doped Yb:YVO4 crystal: A promising material for laser gain medium

Abstract

Abstract Nd co-doped Yb:YVO4 single crystals were grown for the first time by using optical floating zone method to the best of our knowledge. The dimension of grown crystals were ~4–5 mm in diameter and 10–15 mm in length. Powder crystal XRD shows that there is a small shift of diffraction peaks towards the lower angle with Nd doping in the crystal, signifying the expansion of the lattice volume. The quality of the crystal was estimated by Rocking curve measurement. The observed nearly straight fringes in birefringence interferogram ensured the good optical homogeneity of grown crystals. The variation in birefringence was found to be less than 5.64 × 10−4. The dislocation etch pit density was estimated by chemical etching and found to be ~12 × 103/cm2. The measured fluorescence life-time of Yb (0.8 at.%) and Nd (0.8 at.%) co-doped YVO4 crystal is around 581 and 66 μs respectively. The polarized absorption spectra depicted an overall higher absorption for π-polarization (E||c) than the σ-polarization (E┴c). The absorption coefficient at 808 nm & 985 nm corresponding to Nd (0.8 at.%) & Yb (0.8 at.%) ions are ~ 28 & 9.2 cm−1 for π-polarization and ~13.7 & 4.6 cm−1 for σ-polarization, respectively, which is found to be better than the crystals grown by conventional Cz technique. However, the fluorescence lifetime of the crystal grown by OFZ and Cz technique is similar. The present findings revealed that π-polarized absorption of Nd ion at 808 nm can be effectively utilized for pumping Yb:YVO4 gain medium for developing an efficient laser system.