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 (α-BBO) crystals are similar to those of Beta-BBO. However, there is no second order nonlinear effect in Alpha BBO (α-BBO) crystals due to the centrosymmetry in its crystal structure and thus it has no use for second order nonlinear optical processes. Instead, Alpha BBO (α-BBO) crystals 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.
