|
• high optical homogeneity (dn»10-6/cm) and free of inclusion;
• relatively large effective SHG coefficient (about three times that of KDP);
• high damage threshold;
• wide acceptance angle and small walk-off;
• type I and type II non-critical phase matching (NCPM) in a wide wavelength range;
Lithium triborate
(LiB3O5 or LBO) is an excellent nonlinear optical crystal. It combines a wide
transparency range (210-2300 nm), moderate nonlinear coupling, relatively high
damage threshold and good chemical and mechanical properties. LBO crystals have
phase matchable conditions for SHG and THG of infrared lasers, using either
Type I or Type II interactions.
LBO has non-critical phase matching conditions (NCFM) for Type I SHG at
1000-1300nm. In this case, LBO is free of walk-off limitations and, therefore,
long LBO crystals can be used. LBO crystals are free of the grey track effect
and as a result, are very useful in high power green lasers.
Physical
and Chemical Properties
|
Crystal Structure |
Orthorhombic, Point
group mm2, Space group Pna21 |
|
Lattice Parameters |
a=8.4473Å,
b=7.3789Å, c=5.1405Å, z=2 |
|
Density |
|
|
Mohs Hardness |
5.5 |
|
Melting Point |
835 ± |
|
Optical Homogeneity |
Dn~10-6/cm |
|
Absorption
Coefficient |
< 0.03%/cm
@1.064μm, < 0.1%/cm @0.532μm |
|
Thermal Conductivity |
3.5 W/m/K |
|
Thermal Expansion
Coefficient |
ax=10.8x10-5/K,
ay=-8.8x10-5/K, az=3.4x10-5/K |
|
Hygroscopisity |
Non |
Specifications
|
Dimensional
Tolerance |
(W± |
|
(W± |
|
|
Absorption
|
<0.002%@1064nm,
<0.01%@532nm |
|
Cutting
Angle Tolerance |
Dq<
±0.2°, Df< ±0.2° |
|
Wavefront
Distortion |
<λ/8
@632.8 nm |
|
Chamfer |
≤ |
|
Perpendicularity |
<
5 arc min |
|
Parallelism |
<
20 arc sec |
|
Flatness |
<λ/10
@633 nm |
|
Scratch/Dig
|
10/5
per MIL-PRF-13830B |
|
Clear
Aperture |
>
Central 90% |
|
Antireflection
Coating |
R
< 0.2% @1064nm,R < 0.5% @532nm,R<3%@355nm |