Barium Borate (BBO)

KOMLAS offers high quality KTP-, BBO- and LBO- crystals. The right material should be chosen taking into consideration the criteria transmission, damage threshold, efficiency of the nonlinear effect, phase matching range and laser beam quality.

The damage threshold is a function of the wavelength of fundamental and harmonic radiation, pulse duration, beam profile and other parameters. For guidance typical values are given in the table ( = 1064 nm, pulse duration 1.3 ns). max. energy density [J/cm²]: KTP 4.6 BBO 9.9 LBO 18.9

BBO (β-BaB₂O₄) combines superior properties such as wide transparency and phase matching ranges, large nonlinear coefficient, high damage threshold and excellent optical homogeneity. BBO is an efficient NLO crystal for second, third and fourth harmonic generations of Nd:YAG lasers. Due to wide transparence range, high effective nonlinearity and phase matchability down to 410nm, BBO is perfectly suitable as active material for applications in broadly tunable optical parametric oscillators (OPO) and amplifiers (OPA). BBO is the only NLO material which can be used to produce the fifth harmonic generation (5HG) of Nd:YAG lasers at 213 nm.

The large walk-off and the small acceptance angle (1 mrad * cm for type 1 SHG of Nd:YAG) requires excellent laser beam quality to avoid reductions of conversion efficiency. KOMLAS recommend AR- or P-coatings ( for brewster cut) because BBO is a medium hygroscopic crystal.

Crystal structure Point group Space group Lattice constants [Å] Density [g/cm-3] Melting point [°C] Transitition temperature [°C] Mohs hardness Absorption [cm-1] at 1064 nm 532 nm Thermal expansion coefficients [10–6/K] Refractive indices at 1064 nm   532 nm   266 nm   213 nm   Thermo-optic coefficients [10-6/K]

trigonal 3m R3c a= 12.532 b= 12.532 c= 12.717 3.85  1095 925 4.8 < 0.001  < 0.008 c(11) = 4.0,c(33) = 36  n0 = 1.6551 ne = 1.5426 n0 = 1.6749 ne = 1.5555 n0 = 1.7571 ne = 1.6142 n0 = 1.8466 ne = 1.6745 dn0/dT = -9.3 dne/dT = -16.6

Wavelength dispersion of refractive index (Sellmeier equitions)
n₀²= 2.7395 +0.0187/(λ² -0.0182) - 0.0136 λ² (λ in µm, T=20 °C)
n_e²= 2.3748 +0.0123/(λ² -0.0166) - 0.0152 λ² (λ in µm, T=20 °C)

Walk-off for Type 1 SHG @ 1064 nm [mrad] Effective nonlinearity d22[m/V] d31[m/V]

56 (2.22 ±0.08) x 10-12  (0.16 ±0.08) x 10-12

KOMLAS offers:

• Crystal length up to 14 mm and aperture up to 12 mm x 12 mm
• Crystal length down to 0.1 mm for ultrafast lasers
• Dualband and tripleband AR coatings
• P-coatings
• Determination of necessary angular orientation