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Optics
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| BBO |
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 0.19mm to 3.5mm.
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.
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| Specifications |
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| Dimension tolerance |
±0.1mm |
| Angle tolerance |
<0.5° |
| Surface flatness |
l/8@632.8nm |
| Wavefront distortion |
l/8@632.8nm |
| Surface quality |
20-10 |
| Parallelism |
<20 arcsec |
| Perpendicularity |
<5 arcmin |
| Clear aperture |
>80% |
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The
following parameters are typically required to specify
when ordering:
► Sizes
Width x Height x Length (mm)
► Phase matching angle
q and f
► Coating on S1&S2
Protective coating or reflectivity @ wavelength
► Holder
Mounted or Unmounted.
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BBO
typical orientations:
► q¹0°, f=0°, For Type I phase matching
application.
► q¹0°, f=30° , For Type II phase matching
application.
► Brewster cut, q¹0°, f=0°, or 30°, no coating on S1&S2.
► Z-cut, gold coated on X-faces, for Q-switch application.
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Coating
► Protective coating is required to prevent polished surfaces from fogging.
► Anti-reflective coating should be considered if low reflectivity is
required.
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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.
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Phase
matching angle: q and f
q and f are depended on different
applications of frequency conversion. The familiar phase
matching angles are listed below:
SHG@1064nm Type I
q=22.8°, f=0°
SHG@780nm Type I
q=29.9°, f=0°
SHG@532nm Type I
q=47.6°, f=0°
SHG@410nm Type I
q=86.9°, f=0°
SFG@1064+532nm Type I q=31.3°, f=0°
SFG@1064+532nm Type II q=38.5°, f=30°
OPO 532nm pump Type I q=21.0°, f=0°(tunable range 680-2600nm)
OPO 355nm pump Type I q=30.0°, f=0°(tunable range 410-2600nm)
OPO 266nm pump Type II q=39.0°, f=30°(tunable range 295-2600nm)
If you’re not sure to calculate the phase matching
angles, please contact us for assistance.
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BBO Optical properties
Transparence range
189—3500nm
Second harmonic generation range
410—2400nm
Type I phase matching plane
X-Z plane, f=0°
Type II phase matching plane f=30°
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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/°C
dne/dT=-16.6x10-6/℃
NLO coefficients d11=5.8xd36(KDP)
d31=0.05xd11
d22<0.05xd11
Half wave voltage
48Kv@1064nm
Damage threshold
5GW/cm2, 10ns, 1064nm
Sellmeier equations no2(l)=2.7359+0.01878/(l2-0.01822)-0.01354l2
ne2(l)=2.3757+0.01224/(l2-0.01667)-0.01516l2
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BBO Physical properties:
Crystal structure Trigonal,
space group R3c
Cell parameters A=B=12.532Å, C=12.717Å, Z=6Å
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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