Nonlinear optical properties of borate crystals

We have studied the effect of different chemical bonding structures of boro n atoms on the second-order nonlinear optical behavior of berate crystals f rom the chemical bond viewpoint. Several typical berate crystals, including LiB3O5, beta-BaB2O4, BiB3O6, NdAl3(BO3)(4), Ca(4)LnO(BO3)(3), K[B5O6(OH)(4 )].H2O, Eu2B5O9Cl and Ca2B5O9Br, with different chemical bonding structures of boron atoms are investigated. The results show that the different chemi cal bonding structures of boron atoms have a strong effect on the second-or der nonlinear optical behavior of berate crystals. Further, the calculated values show that forming B-O rings would decrease the NLO response of berat e crystals and that [BO3](3-) groups possess larger nonlinear optical contr ibutions than [BO4](5-) groups. (C) 2000 Elsevier Science Ltd. All rights r eserved.