α-BBO (α-BaB2O4) is a negative uniaxial crystal which has large birefringence over a broad
transparent range of 190nm to 3500nm. α-BBO is an excellent crystal
especially in UV and high power applications.
The physical,
chemical, thermal, and optical properties of alpha-BBO crystal are similar to
those of Beta-BBO. However, there is no second order nonlinear effect in
alpha-BBO crystal due to the centrosymmetry in its crystal structure and thus
it has no use for second order nonlinear optical processes. Instead, alpha-BBO
is widely used for fabrication of polarizers, polarizing beam displacers, phase retarders,
birefringent plates, and time delay compensators especially those for UV and
high power lasers.
