Electron-lattice coupling in congruent Co-doped LiNbO_3 : Cr^3^+: ZnO crystal

Abstract

The importance of the role of the ion-lattice coupling in determining the energy levels of Cr^3^+ ions in congruent LiNbO_3 crystals doped with 2.9% of ZnO is demonstrated in this paper. The Racah parameters: B = 533 cm^-1, C = 3244 cm^-1 and the crystal-field intensity Dq = 1527 cm^-1 were determined and the Tanabe-Sugano diagram was constructed. The characteristics of the absorption and the emission spectra of Cr^3^+ ions in these crystals can be explained in terms of the configurational-coordinate diagram in the harmonic approximation, with good agreement obtained. The Huang-Rhys parameter S = 6.86 and the lattice phonon energy hbarω = 343 cm^-1 are also reported in this work.