A NEW-TYPE ULTRAVIOLET SHG CRYSTAL——β-BaB 2 O 4

On the basis of our work An anionic group theory of electro-optical and nonlinear optical effects of the crystals, we first proposed the possibility of searching for new-type SHG crystals among the inorganic materials possessing planar ring groups. Since then, a new-type ultraviolet StIG crystal—β-BaB2O4 has been developed, a crystal with excellent optical homogeneity, anti-deliquescence and easy-working mechanical properties. Various measurements have been made thereupon of its powder sample tests, phase diagram, structural determination and other performance tests. The following parameters of β-BaB2O4 have thus been determined: space group at room temperature R3, melting point 1095℃, phase transition temperature 925±5℃, transparent band range 190—2500mμ, phase matching angle at 539—270mμ 47°, and radiation damage threshold 2GW/em2. Its effective SHG coefficient is 3—6 times larger than that of ADP (at different wavelengths). It is expected that this new crystal will find wide and extensive applications in ultraviolet and near infrared regions.