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BBO Crystal (Beta Barium Borate )

Crystals >>> Nonlinear Crystals >>>  BBO Crystal (Beta Barium Borate )

BBO or beta-BaB2O4 is a nonlinear optical crystal which combines a number of unique features.  These features include wide transparency and phase matching ranges, large nonlinear coefficient, high damage threshold and excellent optical homogeneity.  Therefore,  BBO provides an attractive solutions for various nonlinear optical applications.

  • Second, third, fourth and fifth harmonic generation of Nd:YAG and Nd:YLF laser
  • Frequency-doubling, -tripling and -mixing of Dye lasers
  • Second, third and fourth harmonic generation of Ti:Sapphire and Alexandrite lasers
  • Optical parametric amplifier (OPA) and optical parametric oscillators (OPO)
  • Frequency-doubling of Argon ion, Cu-vapor and Ruby lasers
  • Research and development for advanced laser techniques, including all-solid state wide-tunable lasers, ultrafast pulse lasers, and DUV lasers.


  • Broad phase-matching range from 409.6 nm to 3500nm
  • Wide transmission range from 190 nm to 3500nm
  • Large effective second-harmonic-generation (SHG) coefficient about 6 times greater than that of KDP crystal
  • High damage threshold of 10GW/cm2 for 100ps pulse-width at 1064nm
  • High optical homogeneity with δn≈10-6/cm
  • Wide temperature-bandwidth of about 55C
Main Specification  
Aperture 1x1 ~ 15x15mm
Length 0.01 ~ 25mm
Phase matching angle θ and φ Determined by different kinds of harmonic generation.
Phase matching type Type I or Type II
End configuration Flat or Brewster or Specified

P-coatings, AR-coatings and mounts

Angle tolerance Δθ< 0.5; Δφ< 0.5
Dimension tolerance (W 0.1mm) x (H 0.1mm) x (L + 0.2mm/-0.1mm)
Flatness λ/8 @ 633nm
Surface quality 10/5 scratch/dig per MIL-O-13830A
Parallelism better than 20 arc seconds
Perpendicularity 5 arc minutes
Wavefront distortion less than λ/8 @ 633nm
Clear aperture > 90% central area

To inquiry or order a finished BBO crystals, please provide specifications as listed in the above.  For nonlinear crystals, the maximum conversion efficiency is mainly determined by three specification: crystals length, phase matching type, and phase matching angles(θand φ).

Physical Properties  
Crystal Structure Trigonal, space group R3c
Cell Parameters a = b = 12.532Ä, c = 12.717Ä, Z = 6
Melting Point 1095 5C
Transition Temperature 925 -5C
Optical Homogeneity dn ≈10-6/cm
Hardness 4.5 Mohs 
Density 3.85 g/cm3
Absorption Coefficient < 0.1%/cm (at 1064 nm)
Hygroscopic Susceptibility low
Resistivity > 1011 ohm-cm
Relative Dielectric Constant eT11/e0: 6.7, eT33/e0: 8.1
Tan d, < 0.001
Thermal Expansion Coefficients
(in the range of 25C- 900C)
a, 4 x 10-6/K
c, 36 x 10-6/K
Thermal Conductivity ^c, 1.2 W/m/K; ||c, 1.6 W/m/K
Linear Optical Properties
Transparency Range 189 - 3500 nm
Refractive Indices
at 1.0642 mm
at 0.5321 mm
at 0.2660 mm

ne = 1.5425, no = 1.6551
ne = 1.5555, no = 1.6749
ne = 1.6146, no = 1.7571
Therm-Optic Coefficients dno/dT = - 9.3 x 10-6/C
dne/dT = -16.6 x 10-6/C
Sellmeier Equations: no2(l) = 2.7359+0.01878/(l2-0.01822)-0.01354 l2
l) = 2.3753+0.01224/(l2-0.01667)-0.01516 l2
Nonlinear Optical Properties
Phase-matchable SHG range 189 - 1750nm
NLO coefficients d11 = 5.8 x d36(KDP)
d31 = 0.05 x d11
d22< 0.05 x d11
Electro-Optic Coefficients g11 = 2.7 pm/V, g22, g31< 0.1 g11
Half-Wave Voltage 48 KV (at 1064 nm)
Damage Threshold
at 1.064 mm
at 0.532 mm

5 GW/cm2 (10 ns); 10 GW/cm2 (1.3 ns)
1 GW/cm2 (10 ns); 7 GW/cm2 (250 ps)



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