Barium Borate (α -BBO) Crystals

High temperature form BBO (α -BaB2O4) are negative uniaxial crystals. They have large birefringence over a broad transparent range of 190nm to 3500nm. We succeeded in growing these crystals to large sizes. The physical, chemical, thermal and optical properties of α -BBO crystals are similar to those of ß -BBO. However, the nonlinear optical properties of α -BBO crystals are nonexistent due to the centric symmetry with its crystal structure. α -BBO crystals are not recommended for NLO processes.

a -BBO are excellent crystals to replace Calcite, TiO2 LiBbO3 etc. in Glan Taylor and Glan Thompson Polarizers as well as walk-off Beamsplitters, especially for high power and UV Polarizers. This is due to their unique UV transparency, good mechanical properties and high damage threshold. We also manufacture and supplies Glan Laser, Glan Taylor, Glan Thompson Polarizers and other beam displacers from high quality α -BBO crystals to replace Calcites in many applications, especially in UV and high power operations.

Basic Properties of α -BBO Crystals

Transparency Range: 190 - 3500nm, see transparency curve

Density: 3.85g/cm³

Therm-Optic Coefficients: 
dn_o/dT = - 9.3X10^-6/°C
dn_e/dT = -9.3X10^-6/°C

Damage Threshold: 
@1064nm 1GW/cm²
@355nm 500MW/cm²

Optical Homogeneity: Δ n~10^-6/cm²

Mohs Hardness: 4.5

Hygroscopic Susceptibility: Low

Thermal Expansion Coefficients (in the range of 25°C-900°C):
a_a = 4X10^-6/° K   a_c = 36X10^-6/° K

Linear Absorption Coefficients: α <0.005cm^-1 from 300nm to 2300nm

Refractive Indices, Birefringence (Δn_e = n_o) and Walk-off Angle at 45° (β): 
@1.0642μm  n_e=1.5379  n_o=1.6579  Δn=-0.1199  ρ=-4.287°
@0.5321μm  n_e=1.5534  n_o=1.6776  Δn=-0.1241  ρ=-4.387°
@0.2660μm  n_e=1.6114  n_o=1.7617  Δn=-0.1503  ρ=-5.082°

Capabilities of Polarizer with α -BBO

Transparency Curve of α -BBO