Investigation of optical and spectroscopic properties of Nd co-doped Yb:YVO4 single crystals grown by OFZ method

Abstract

Nd (0.8 at.%) co-doped Yb (0.8 and 3.0 at.%):YVO4 single crystals were grown by optical floating zone technique for the first time to the best of our knowledge. The absorption spectra revealed strong absorption for π-polarization (E||c) than the σ-polarization (E⊥c) for both the Yb concentrations due to anisotropy of the crystal. The estimated effective Judd-Ofelt parameters are 11.8675 × 10−20, 5.1577 × 10−20 and 7.3755 × 10−20 cm−2. Spectroscopic quality factor of Nd co-doped Yb:YVO4 are 0.70. which is lower than that of Nd (1.0 at.%) doped YVO4 (0.97), which indicates the energy transfer from Nd3+ ion to Yb3+ ion inside the host matrix. The estimated emission cross-section of 4F3/2 → 4I11/2 Nd transition with an excitation at 808 nm for both the concentrations of Yb is ∼4.0 × 10−19 cm2 which is almost same as estimated by Bhaumik et al. (2014) [21] for Nd:YVO4. Hence emission cross-section of 4F3/2 → 4I11/2 Nd transition is not effected by Yb co-doping. Also the PL intensity of Yb at 1010 nm enhances with Yb co-doping for same Nd (0.8 at.%) this is because the Nd3+ ion effectively excites the Yb3+ ion in upper state. Therefore Nd3+ ion acts as excellent sensitizer for Yb:YVO4 laser gain medium and make efficient pumping in the gain medium.