Mechanism For Linear And Nonlinear Optical Effects In Crystals Of The Sr2be2b2o7 Family

Electronic structure calculations of Sr2Be2B2O7 (SBBO) family crystals including Sr2Be2B2O7, BaAl2B2O7, and K2Al2B2O7 have been performed based on a plane-wave pseudopotential method. Moreover, the linear optical coefficients and the static second-harmonic generation (SHG) coefficients of BaAl2B2O7 and K2Al2B2O7 are calculated at the independent-particle level. The calculated refractive indices and SHG coefficients are in good agreement with experimental values. In addition, a real-space atom-cutting method is adopted to analyze the respective contributions of the cations and anionic group to optical response. The results show that in these crystals, when the radii of the cations increase, their contributions to the SHG effect become slightly more pronounced, however, the contributions to the SHG coefficients from the (BO3)(3-) and (AlO4)(5-) anionic groups are dominant and comparable. (C) 2003 American Institute of Physics.