Lithium Triborate (LiB₃O₅), commonly known as LBO, is a high-performance nonlinear optical crystal widely used in solid-state laser systems for frequency conversion. Owing to its high laser damage threshold, broad transparency range, excellent optical homogeneity, and stable phase-matching behavior, LBO has become one of the most reliable crystals for high-power and high-average-power laser applications.
LBO supports both Type I and Type II phase matching and is particularly well suited for second harmonic generation (SHG), third harmonic generation (THG), sum-frequency generation (SFG), and optical parametric oscillation (OPO), especially when long-term thermal and optical stability are required.
Physical & Mechanical Properties
| Parameter | Value |
|---|---|
| Density | 2.47 g·cm⁻³ |
| Melting Point | 834 °C |
| Mohs Hardness | 6 |
| Thermal Conductivity | 3.5 W·m⁻¹·K⁻¹ |
| Thermal Expansion Coefficients | aₓ = 10.8 × 10⁻⁵ K⁻¹ aᵧ = −8.8 × 10⁻⁵ K⁻¹ a_z = 3.4 × 10⁻⁵ K⁻¹ |
| Crystal Structure | Orthorhombic System |
| Lattice Parameters | a = 8.4473 Å, b = 7.3788 Å, c = 5.1395 Å |
Optical & Nonlinear Properties
| Parameter | Value |
|---|---|
| Transparency Range | 160 – 2600 nm |
| SHG Phase-Matchable Range | 551 – 2600 nm (Type I)790 – 2150 nm (Type II) |
| Thermal-Optic Coefficient | dnₓ/dT = −9.3 × 10⁻⁶ °C⁻¹ dnᵧ/dT = −13.6 × 10⁻⁶ °C⁻¹ dn_z/dT = −(6.3–2.1) × 10⁻⁶ °C⁻¹ |
| Absorption Coefficient | < 0.1% @1064 nm < 0.3% @532 nm |
| Angle Acceptance | 6.54 mrad·cm⁻¹ (φ, Type I, 1064 nm SHG) 15.27 mrad·cm⁻¹ (φ, Type II, 1064 nm SHG) |
| Temperature Acceptance | 4.7 °C·cm⁻¹ (Type I, 1064 nm SHG) 7.5 °C·cm⁻¹ (Type II, 1064 nm SHG) |
| Spectral Acceptance | 1.0 cm⁻¹ (Type I, 1064 nm SHG) 1.3 cm⁻¹ (Type II, 1064 nm SHG) |
| Walk-off Angle | 0.60° (Type I, 1064 nm SHG) 0.12° (Type II, 1064 nm SHG) |
Nonlinear Optical Coefficients (pm·V⁻¹)
| Coefficient | Value |
|---|---|
| d₃₁ | 1.05 ± 0.09 |
| d₃₂ | −0.98 ± 0.09 |
| d₃₃ | 0.05 ± 0.006 |
Effective nonlinear coefficients depend on crystal orientation and phase-matching configuration (Type I / Type II).
Standard Manufacturing Specifications
| Item | Specification |
|---|---|
| Dimension Tolerance | W × H ±0.1 mm, L +0.5 / −0.1 mm |
| Angular Tolerance | Δθ ≤ 0.25°, Δφ ≤ 0.25° |
| Parallelism | < 20 arc sec |
| Perpendicularity | < 5 arc min |
| Chamfer | 0.1 mm × 45° |
| Clear Aperture | ≥ 90% |
| Scratch & Dig | 10/5 |
| Surface Flatness | λ/8 @ 633 nm |
| Wavefront Distortion | λ/8 @ 633 nm |
| Damage Threshold | >1 GW·cm⁻² (@1064 nm, TEM₀₀, 10 ns, 10 Hz) >0.5 GW·cm⁻² (@532 nm, TEM₀₀, 10 ns, 10 Hz) |
Key Advantages
- Very high laser damage threshold for high-power and high-repetition lasers
- Broad transparency range from deep UV to mid-IR
- Excellent optical homogeneity (dn < 10⁻⁶·cm⁻¹)
- Large effective SHG coefficient, ~3× that of KDP
- Good chemical and mechanical stability for long-term operation
- Suitable for non-critical phase matching (NCPM) in selected configurations
Typical Applications
- Frequency Conversion: SHG, THG, and SFG for Nd:YAG and other solid-state lasers
- Optical Parametric Oscillators (OPOs): Broad tunability with stable output
- Laser Spectroscopy: Multi-wavelength generation for analytical and scientific systems
- Medical & Industrial Lasers: UV and visible laser generation for diagnostics, processing, and micromachining
Shape Optics Capabilities
Shape Optics supplies high-quality LBO crystals for research, industrial, and OEM laser systems.
Available Configurations
- Maximum size: up to 30 × 30 × 30 mm
- Length / thickness: 0.02 mm – 60 mm
- Crystal cut & orientation: custom on request
- Optical coatings: AR and custom coatings available
With over 20 years of optical manufacturing experience, Shape Optics provides precision crystal processing, advanced polishing, and in-house coating solutions across the UV–NIR spectrum. Our production emphasizes consistency, performance, and compliance with international optical standards.
For reliable and high-performance nonlinear optical solutions, contact Shape Optics to discuss your LBO crystal requirements.