BBO is a new ultraviole frequency doubling crystal.

Features of BBO Crystals:

  • Broad phase matchable range from 409.6 nm to 3500 nm;
  • Wide transmission region from 190 nm to 3500 nm;
  • Large effective second-harmonic-generation (SHG) coefficient about 6 times greater than that of KDP  crystal;
  • High damage threshold;
  • High optical homogeneity with δn ≈10-6/cm;
  • Wide temperature-bandwidth of about 55℃.

Basic properties:

Crystal Structure
Trigonal,Space Group R3c
Lattice Parameter
Melting Point
About 1095℃
Mohs Hardness
3.85 g/cm3
Thermal Expansion Coefficients
α11=4 x 10-6/K; α33=36x 10-6/K
Thermal Conductivity Coefficients
⊥c: 1.2W/m/K; //c: 1.6W/m/K
Transparency Range
SHG Phase Matchable Range
409.6-3500nm  (Type I)      525-3500nm (Type II)
Thermal-optic Coefficients (/℃)
dno/dT=-16.6x 10-6/℃
dne/dT=-9.3x 10-6/℃
Absorption Coefficients
<0.1%/cm(at 1064nm)  <1%/cm(at 532nm)
Angle Acceptance
0.8mrad·cm  (θ, Type I, 1064 SHG)
1.27mrad·cm  (θ, Type II, 1064 SHG)
Temperature Acceptance
Spectral Acceptance
Walk-off Angle
2.7° (Type I  1064 SHG)
3.2° (Type II  1064 SHG)
NLO Coefficients
deff(I)=d31sinθ+(d11cos3Φ- d22 sin3Φ) cosθ                   
deff (II)= (d11 sin3Φ + d22 cos3Φ) cos2θ
Non-vanished NLO susceptibilities
d11 = 5.8 x d36(KDP)
d31 = 0.05 x d11
d22 < 0.05 x d11
Sellmeier  Equations
(λ in μm) 
Electro-optic coefficients
γ22 = 2.7 pm/V
Half-wave voltage
7 KV (at 1064 nm,3x3x20mm3)
Technical Parameters:

  • Dimension tolerance: (W±0.1mm)x(H±0.1mm)x(L+0.5/-0.1mm)  (L≥2.5mm)
                                    (W±0.1mm)x(H±0.1mm)x(L+0.1/-0.1mm)  (L<2.5mm)
  • Clear aperture: central 90% of the diameter
  • No visible scattering paths or centers when inspected by a 50mW green laser
  • Flatness: less than λ/8 @ 633nm
  • Transmitting wavefront distortion: less than λ/8 @ 633nm
  • Chamfer:≤0.2mm x 45°
  • Chip: ≤0.1mm
  • Scratch/Dig code: better than 10/ 5 to MIL-PRF-13830B
  • Parallelism: ≤20 arc seconds
  • Perpendicularity: ≤5 arc minutes
  • Angle tolerance: ≤0.25
  • Damage threshold[GW/cm2]: >1   for 1064nm, TEM00, 10ns, 10HZ (polished only) 
                                                >0.5 for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
                                                >0.3 for 532nm,  TEM00, 10ns, 10HZ (AR-coated)