Nonlinear optical absorption and energy structure of LiNbO3andα-LiIO3crystals

An experimental investigation was made of the nonlinear absorption in LiNbO 3 and α -LiIO 3 crystals in the photon energy range + h( ω 1 + ω 2 )≤5.2 eV. In the case of LiNbO 3 the nonlinear absorption was due to two-photon allowed-forbidden transitions. The magnitude of the two-photon absorption and its spectral dependences were used to determine some of the parameters of the energy band structure. In the case of α -LiIO 3 the two-photon absorption coefficient was β < 4 × 10 −4 cm/MW in the range + h( ω 1 + ω 2 )≤5.2 eV. This indicated that frequency conversion in the ultraviolet range could be carried out in α -LiIO 3 over a wider frequency range than in LiNbO 3 .