Description
BBO Crystal
—a widely used nonlinear crystal for frequency conversion in the ultraviolet, visible and near-infrared
BBO Crystal is a one of the most important nonlinear optical crystals, beta-barium borate (β-BaB2O4，β-BBO) combines many outstanding features such as its high nonlinear optical coefficients, low group-velocity dispersion, broad transparency range (189–3500 nm) and high damage threshold. This unique combination ensures β-BBO crystal a promising candidate for a wide range of nonlinear optical applications such as frequency converters and optical parametric oscillators. In the realm of quantum optics, β-BBO crystal can be used to generate entangled photon pairs and ten-photon entanglement.
BBO nonlinear crystal is a negative uniaxial crystal, which provides phase matching for various second-order interactions almost over its entire transparency range (from 185 nm to 3.3 µm, as deduced from the transmittance measurements using crystal samples of several mm thickness), making it a widely used crystal for nonlinear frequency conversion in the ultraviolet, visible and near-infrared. In that regard, BBO crystal is the most important nonlinear crystal for near infrared optical parametric chirped pulse amplifiers, which currently deliver few optical cycle pulses with high average and ultrahigh peak powers.
Physical and Chemical Properties
Linear Optical Properties
Property
Value
Chemical formula
BaB2O4
Crystal structure
trigonal, 3m
Lattice Parameter
a=b=12.532Å,c=12.717Å, Z=6
Mass density
3.85 g/cm3
Moh hardness
4
Melting point
About 1095°C
Thermal conductivity
1.2 W/m/K (⊥c); 1.6 W/m/K (//c)
Thermal expansion coefficient
α,4×10-6/K; c,36×10-6/K
Birefringence
negative uniaxial
at 1.0642 μm
at 0.5321 μm
at 0.2660 μm
ne = 1.5425, no = 1.6551
ne = 1.5555, no = 1.6749
ne = 1.6146, no = 1.7571
no2(λ) = 2.7359+0.01878/(λ2-0.01822)-0.01354λ2
ne2(λ) = 2.3753+0.01224/(λ2-0.01667)-0.01516λ2
Property
Value
Transparency Range
189 – 3500 nm
Absorption Coefficient
α<0.1%/cm @1064nm
RefractiveIndices
Sellmeier Equations(λ in μm)
SHG Phase Matchable Range
409.6 ∼ 3500nm (Type I); 525 ∼ 3500nm (TypeII)
NLO coefficients
d11= 5.8 x d36(KDP); d31 = 0.05 x d11; d22< 0.05 x d11
deff(I)=d31sinθ+ (d11cos3φ – d22sin3φ)cosθ
deff(II)=(d11sin3φ+ d22cos3θ)cos2θ
Therm-Optic Coefficients
dno/dT = – 9.3 x 10-6/◦C
dne/dT = -16.6 x 10-6/◦C
Electro-Optic Coefficients
g11= 2.7 pm/V, g22, g31< 0.1 g11
Half-Wave Voltage
48 KV (at 1064 nm)
Damage Threshold
at 1.064 μm
5 GW/cm2 (10 ns); 10 GW/cm2 (1.3 ns)
at 0.532 μm
1 GW/cm2 (10 ns); 7 GW/cm2 (250 ps)
