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BBO Crystal ß-Barium Borate
ß-BaB2O4
PHOTOX supplies flux-grown BBO of high optical homogeneity produced under a strict regime of quality control. Because of its high nonlinear coefficient, wide transparency and phase matchable range, it is often the preferred material for harmonic generation and frequency mixing of a variety of lasers such as Dye, Ti:Sapphire, Alexandrite, Argon ion, Cu-vapor, Ruby and Nd doped solid state lasers. In tunable UV generation, wavelengths down to 205nm can be obtained by direct SHG and 189nm by sum frequency generation. Its high damage threshold also makes it suitable for intense pulsed laser frequency conversion or OPO and OPA. Its attractive features and basic properties are summarized below.
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Broad phase-matchable range from 409.6nm - 3500nm. |
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Wide transmission region from 190nm - 3500nm. |
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Large effective second-harmonic-generation (SHG) coefficient: approximately 6 times greater than that of KDP. |
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High damage threshold of 10 GW/cm2 for 100 ps pulse-width at 1064nm. |
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High optical homogeneity with delta n=10-6/cm. |
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Wide temperature-bandwidth of about 55°C. |
Physical Properties |
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| Crystal structure | Trigonal, space group R3c |
| Lattice parameters | a=b=1.253nm, c=1.272nm, Z=6 |
| Melting point | 1095±5°C |
| Phase transition temperature | 925±5°C |
| Temperature stability | 8 x KDP |
| FWHM of phase matched SHG | 55°C |
| Mohs hardness | 4.5 |
| Density | 3.85 g/cm3 |
| Absorption coefficient @ 1064nm | <0.1%/cm3 |
| Hygroscopic susceptibility | low |
| Resistivity | >1011 ohm-cm |
| Relative dielectric constant | eT11/ eo:6.7; eT33/ eo:8.1 Tan d, <0.001 |
| Thermal expansion coefficients (25°-900°C) | a, 4 x 10-6/K; c, 36 x 10-6/K |
| Thermal conductivity | 1.2 W/m/K; ||c, 1.6 W/m/K |
Optical Properties |
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| Refractive index, 1064nm | no=1.65, ne=1.54 |
| Refractive index, 532nm | no=1.67, ne=1.55 |
| Refractive index, 266nm | no=1.75, ne=1.61 |
| Optical homogeneity Dn | 10-6 cm -1 |
| Transparency range | 189-3500 nm |
| Phase matchable range (SHG) | 189-1750 nm |
| Effective nonlinear coefficient | 4-6 x KDP |
| Acceptance angle | 0.2-1 mrad-cm |
| Walk-off angle, from SHG-5HG of Nd:YAG laser | 3.2°-5.5° |
| Thermo-optic coefficients | dno/dT= -9.3 x 10-6/°C |
| dne/dT=-16.6 x 10-6/°C | |
| Sellmeier equations | |
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n2o(l) = 2.7359+0.01878/(l 2-0.01822)-0.01354 x l2( in µm) n2e(l) = 2.3753+0.01224/(l2-0.01667)-0.01516 x l2 |
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Finished Quality Indications |
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| End faces flatness | < l/8 @ 633nm (transmitting wavefront distortion also) |
| Scratch/Dig | 10/5 to MIL-0-13830 A |
| Clear aperture | >90% central area |
| Dimension tolerance | W±0.1mm |
| H±0.1mm x | |
| L+0.2mm*/-0.1mm | |
| Parallelism | >20 arc seconds |
| Perpendicularity | 5 arc minutes |
| Angle tolerance | D q ±0.5°, Df<±0.5° |
| * Ultra thin pieces will have a different figure from this.
The crystals are guaranteed to the above specifications Coating and MountThe BBO may be provided with AR/P coatings or cut with Brewster's angle faces for intra-cavity use. Mounts are also available. Handling & Technical SupportBBO should be kept and used in dry conditions as it is mildly hygroscopic. Care must be taken to protect its soft polished faces from scratching and dust. The surface can be cleaned with a piece of soft silk dampened with pure organic solvents, such as a 50:50 mixture of highly pure alcohol and ether. We will be pleased to offer recommendations, technical advice and support, if you let us have the basic parameters of your laser system and your application for the crystal.
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