NONLINEAR-OPTICAL MATERIALS BASED ON MBE2BO3F2 (M=NA,K)

MBe2BO3F2 (M = Na,K) have been discovered to be nonlinear optical (NLO ) materials for UV applications. They have relatively large NLO coeffi cients: d(eff) is about 2.5 times as large as that of KH2PO4 (lambda = 1079 nm, Nd:YAP laser), the UV cutoff wavelengths are as short as 155 nm, and they have a moderate birefringence of nearly 0. 10. Their str uctures are characterized by an infinite sheet which is formed by six- membered rings [Be2BO6F2] with Be-0 and B-0 edges in common. Such stru ctures are favorable for good NLO properties. These NLO properties mak e MBe2BO3F2 promising candidates for vacuum UV NLO materials.