New low symmetry centres of Yb3+ impurities in lithium niobate single crystal

Abstract The results of optical spectroscopy and electron paramagnetic resonance studies of Yb 3+ impurities in congruent LiNbO 3 host crystal ([Li]/[Nb] = 0.94) were reported at low temperatures. Fine and hyperfine EPR transitions were observed for different isotopes of Yb 3+ ion. The spectra indicate the presence of few magnetically non-equivalent Yb 3+ sites in unit cell of the LiNbO 3 . Mainly ytterbium centers with C 1 lowest point symmetry group are detected; axial symmetry centers are not recognized. The values of the components of the g and A tensors are estimated. The temperature dependence of the intensity, peak-to-peak linewidth and g -parameter of the EPR central line ( 170 Yb) suggests the presence of the Yb 3+ –Yb 3+ pairs in lithium niobate host crystal doped with ytterbium.