Phonons in nonlinear optical δ-BiB3O6 crystal: Raman and infrared spectra and lattice dynamics

• Raman and IR spectra of δ-BiB3O6 were measured.
• Assignment of vibrational modes was proposed.
• Large LO–TO splitting was observed for a few Raman modes.
• Origin of nonlinear optical properties in δ-BiB3O6 was discussed.

δ-BiB3O6 nonlinear optical single crystals were grown and they were characterized by Raman scattering and infrared spectroscopy. Symmetry of modes was established and the mode assignment was proposed on the basis of classical lattice dynamics calculations. Raman data showed that nonlinear optical properties of δ-BiB3O6 may be associated both with the Bi3+ ions and BO4 groups. They also show that δ-BIBO is a promising medium for up- and down-Raman laser-frequency converters.