High Temperature form BBO ( a-BaB2O4 ) is a negative uniaxial crystal. It has large birefringence over the broad transparent range from 189 nm to 3500 nm. The physical, chemical, thermal and optical properties of a-BBO crystal are similar to those of b-BBO. However, the nonlinear optical properties of a-BBO crystal is vanished due to the centric symmetry with its crystal structure. It is not recommended to use for NLO processes.
a -BBO is an excellent crystal to replace Calcite, TiO2 , and LiNbO3 , etc. in Glan-Taylor and Glan-Thompson polarizers as well as walk-off beam splitters, especially for high power and UV polarizer, due to its unique UV transparency, good mechanical properties and high damage threshold.
