LBO Crystal

• broad transparency range from 160nm to 2600nm.
• 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  2.47 g/cm3
Mohs Hardness  5.5
Melting Point  835 ±5°C
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=10.8×10-5/K, ay=-8.8×10-5/K, az=3.4×10-5/K
Hygroscopisity  Non


Dimensional Tolerance (W±0.1mm) x (H±0.1mm) x (L+0.2/-0.1 mm) L>2mm
(W±0.1mm) x (H±0.1mm) x (L±0.1 mm) L<2mm
Absorption <0.002%@1064nm, <0.01%@532nm
Cutting Angle Tolerance Dq< ±0.2°, Df< ±0.2°
Wavefront Distortion <λ/8 @632.8 nm
Chamfer ≤ 0.15 mm x 45°
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