β-BBO is a excellent nonlinear optical crystal. The phase transition point of the crystal is lower than its melting point, so the crystal must be grown by flux method. It is known that low growth rate and flux contamination are the two shortcomings of this method. β-BBO is a excellent nonlinear optical crystal. The phase transition point of the crystal is lower than its melting point, so the crystal must be grown by flux method. It is known that low growth rate and flux contamination are the two shortcomings of this method.