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BBO  is an outstanding crystal for many applications in nonlinear optics and electro-optics. BBO is a colorless trigonal uniaxial crystal with low hygroscopic susceptibility. Its transparency range is from 0.19μm to 3.5μm.

BBO is an efficient nonlinear crystal for second, third, fourth and fifth harmonic generators of Nd: Laser, dye lasers and ultrafast Ti:Sapphire lasers. It has also excellent performance in optical parametric amplifier, oscillators, etc.
BBO typical orientations
►θ0°, φ=0°, For Type I phase matching application.
θ0°, φ=30°, For Type II phase matching application.
►Brewster cut,θ0°, φ=0°, or 30°, no coating on S1&S2.
►Z-cut, gold coated on X-faces, for Q-switch application.

Phase matching angle: θ and φ
q and f are depended on different applications of frequency conversion.
If you're not sure to calculate the phase matching angles, please contact us for assistance.

General Specifications
Dimension tolerance
Thickness tolerance
Angle tolerance
Surface flatness
Wavefront distortion
Surface quality
<20 arcsec
<5 arcmin
Clear aperture
Typical Sizes

Aperture: 5x5mm, 6x6mm, 7x7mm, 10x10mm
Thickness: 0.1mm, 0.2m, 0.5mm, 1.0mm, 2.0mm, 3.0mm, 5.0mm

Protective coating is required to prevent polished surfaces from fogging.
Anti-reflective coating should be considered if low reflectivity is required.
Ultra thin BBO Plate
The minimum thickness of BBO we can polish is 0.005mm, the ultra thin BBO is used for frequency conversion of ultra fast laser with femtosecond pulse width.
For frequency conversion of ultrafast lasers such as Ti:sapphire and Dye laser with femtosecond pulse width.
The main concern is fs pulse broadening induced by group velocity mismatching(GVM) or group velocity dispersion. The suggested thickness of BBO crystals is less than pulse width divides.
Phase matching angle
θ and φ are depended on different applications of frequency conversion. The familiar phase matching angles are listed below:
SHG@1064nm Type I θ=22.8°, φ=0°
SHG@780nm Type I θ=29.9°, φ=0°
SHG@532nm Type I θ=47.6°, φ=0°
SHG@410nm Type I θ=86.9°, φ=0°
SFG@1064+532nm Type I θ=31.3°, φ=0°
SFG@1064+532nm Type II θ=38.5°, φ=30°
OPO 532nm pump Type I θ=21.0°, φ=0°(tunable range 680-2600nm)
OPO 355nm pump Type I θ=30.0°, φ=0°(tunable range 410-2600nm)
OPO 266nm pump Type II θ=39.0°, φ=30°(tunable range 295-2600nm)
BBO Optical properties
Transparence range 189—3500nm
Second harmonic generation range 410—2400nm
Type I phase matching plane X-Z plane, φ=0°
Type II phase matching plane φ=30°
Refractive indices ne=1.5425, no=1.6551@1064nm
  ne=1.5555, no=1.6749@532nm
  ne=1.6146, no=1.7571@266nm
Therm-optic coefficients dno/dT=-9.3x10-6/℃
NLO coefficients d11=5.8xd36(KDP)
Half wave voltage 48KV@1064nm
Damage threshold 5GW/cm2, 10ns, 1064nm
Sellmeier equations no2(λ)=2.7359+0.01878/(λ2-0.01822)-0.01354λ2
BBO Physical properties:
Crystal structure Trigonal, space group R3c
Cell parameters A=B=12.532A, C=12.717A, Z=6
Melting point 1095℃
Transition temperature 925℃
Mohs hardness 4.5
Optical coefficient <0.1%/cm @1064nm
Density 3.85g/cm3
Hygroscopic susceptibility Low
Resistivity >1011 ohm-cm
Thermal expansion coefficients ⊥C, 4x10-6/K;∥C, 36x10-6/k
Thermal conductivity ⊥C, 1.2w/m/k;∥C, 1.6w/m/k
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