A high-temperature form of nonlinear crystal beta-barium borate (BBO) is available that is a negative uniaxial crystal. The a-BBO has a birefringence of about 0.14 and is transparent from 189 to 3500 nm. The crystal is chemically stable, nonhydroscopic, and is hard, like glass. The refractive indices are no=1.67 and ne=1.53 in the visible wavelength range. Applications include optical isolators and circulators for fiberoptic systems, Glan-Taylor and Glan-Thompson polarizers, walk-off beamsplitters, and high-power UV polarizers.
Casix in USA, Monterey Park, CA