Beta-barium borate (BBO) has the following exceptional properties that make it a very important nonlinear crystal.

BBO is grown with the flux method. It is a negative uniaxial crystal, with ordinary refractive-index (no) larger than extraordinary refractive-index (ne).

  • SHG phase-matching range from 410 nm to 2100 nm
  • Transmission from 190 nm to 3500 nm
  • Large effective nonlinear coefficient
  • High damage threshold
  • Wide temperature-bandwidth of about 55°C


Transmitting wavefront distortion 1/8 @633nm
Flatness 1/8 @633nm
Scratch/Dig code 10/5 to MIL-O-13830A
Parallelism better than 20 arc seconds
Perpendicularity 15 arc minutes
Angle tolerance Dq < +/-0.3° Df < +/-0.3°
AR coating R< 0.1% at 1064nm and R<0.4% at 532 nm
Quality Warranty Period one year under proper use

The Sellmeier equations (λ€in μm):

  • no2=2.7359+0.01878/(λ2-0.01822)-0.01354λ2
  • ne2=2.3753+0.01224/(λ2-0.01667)-0.01516λ2


BBO is of particular importance in the visible and far UV. A wide variety of phase-matching applications are possible, including the following:

  • Second, third, fourth and fifth harmonic generation of Nd doping lasers.
  • Frequency-doubling, -tripling and -mixing of Dye lasers.
  • Second, third and fourth harmonic generation of Ti:Sapphire lasers.
  • Optical parametric amplifier (OPA) and optical parametric oscillators (OPO).


BBO has a low susceptibility to the moisture. The user is advised to provide dry conditions for both the use and preservation of BBO.

BBO is relatively soft and therefore requires precautions to protect its polished surfaces.

When angle adjusting is necessary, keep in mind that the acceptance angle of BBO is small

Standard Products (BBO)

Part Number Dimension Application Coating
BBO-335 3x3x5mm S(T)HG@1064nm AR coating
BBO-4410 4x4x10mm S(T)HG@1064nm AR coating
BBO-551 5x5x1mm S(T)HG@800nm P-coating
BBO-5501 5x5x0.1mm S(T)HG@800nm P-coating
BBO-6601 6x6x0.1mm S(T)HG@800nm P-coating
BBO-6602 6x6x0.2mm S(T)HG@800nm P-coating
BBO-6605 6x6x0.5mm S(T)HG@800nm P-coating
BBO-661 6x6x1mm S(T)HG@800nm P-coating
BBO-662 6x6x2mm S(T)HG@800nm P-coating
BBO-847 8x4x7mm SHG for Dye laser P-coating
BBO-101005 10x10x0.5mm SHG @ 800 nm P-coating
BBO-10101 10x10x1mm SHG @ 800 nm P-coating