Beta-Barium Borate (BBO), with the chemical formula β-BaB₂O₄, is a nonlinear optical (NLO) crystal renowned for its superior optical properties and broad transmission range (190–3500 nm). With a high nonlinear coefficient and exceptional thermal and mechanical stability, BBO is a preferred choice for frequency conversion applications, including SHG, THG, and optical parametric oscillators (OPOs).
BBO exhibits a high damage threshold (>10 GW/cm² at 1064 nm), low absorption loss, and excellent phase-matching capabilities. Its uniaxial structure, characterized by high homogeneity and minimal walk-off angles, supports both type I and type II phase matching, enabling precise frequency tuning for ultraviolet (UV) to infrared (IR) outputs. This crystal’s durability, coupled with its compatibility with advanced coatings, makes it an indispensable material in high-power laser systems, spectroscopy, and electro-optic applications.
BBO crystals are versatile and widely utilized in a variety of high-performance applications:
| Property | Value |
|---|---|
| Crystal Structure | Trigonal, Space group R3c |
| Lattice Parameter | a = b = 12.532 Å, c = 12.717 Å, Z = 6 |
| Density | 3.85 g/cm³ |
| Melting Point | ~1095°C |
| Mohs Hardness | 4 |
| Thermal Conductivity | 1.2 W/m·K (⊥ axis), 1.6 W/m·K (‖ axis) |
| Thermal Expansion Coefficient | a₁ = 4 × 10⁻⁶/K, a₂ = 36 × 10⁻⁶/K |
| Property | Value |
|---|---|
| Transparency Range | 190–3500 nm |
| SHG Phase Matching Range | 409.6–3500 nm (Type I), 525–3500 nm (Type II) |
| Damage Threshold | >10 GW/cm² @ 1064 nm |
| Temperature Acceptance | ~55°C |
| NLO Coefficients | d₃₁ = 2.7 pm/V, d₃₆ = 5.8 × d₆₆ (KDP) |
| Refractive Indices | no = 1.655 (532 nm), ne = 1.542 (1064 nm) |
| Walk-Off Angle | 2.7° (Type I), 3.2° (Type II) |
| Attribute | Value |
|---|---|
| Dimensions | 0.1–25 mm thickness |
| Surface Quality | 10/5 (Scratch-Dig Precision Grade) |
| Parallelism | <20 arc seconds |
| Angle Tolerance | Δθ < 0.25°, Δφ < 0.25° |
| Damage Threshold | >1 GW/cm² @ 1064 nm, 10 Hz |
Graphs depicting BBO’s transparency curve and phase-matching characteristics are provided for precision laser applications.
| Dimensions (mm) | Coatings | Applications | Price (USD) |
|---|---|---|---|
| 6 × 6 × 0.1 | AR@515 nm | SHG@1030 nm, Type I | $450 |
| 6 × 6 × 0.2 | AR@800 nm | THG@800 nm, Type I | $500 |
| 6 × 6 × 0.5 | BBAR@1064 nm | FOHG@1064 nm, Type II | $550 |
| Custom | Upon request | Tailored to user specifications | Contact for Pricing |
