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Newlight BBO features

Broad phase-matching range from 410 nm to 2100 nm

Useful optical transmission from 190 nm to 3500 nm

Large effective second-harmonic-generation (SHG) coefficient about 6 times
greater than that of KDP crystal

High damage threshold of 10 GW/cm2 for 100ps pulse-width at 1064nm

High optical homogeneity with δn ~ 10-6/cm

Wide temperature-bandwidth of about 55oC

Low thermo-optic coefficient

Structural and Physical Properties

Crystal Structure	Trigonal, space group R3c, Point group 3m
Cell Parameters	a = b = 12.532 Å, c = 12.717Å, Z = 6
Melting Point	1095 °C
Transition Temperature	925 °C
Mohs Hardness	4
Density	3.85 g/cm3
Specific Heat	1.91 J/cm3x K
Hygroscopic Susceptibility	Low
Thermal Expansion Coefficients	a, 4 x 10-6/K; c, 36 x 10-6/K
Thermal Conductivity	⊥c, 1.2 W/m/K; //c, 1.6 W/m/K

Linear Optical Properties

Transparency Range	189-3500 nm
Optical Homogeneity	δn ~ 10-6/cm
Absorption Coefficient	< 0.1%/cm (at 1064nm)
Sellmeier Equations (λ in µm)	no2=2.7359+0.01878/(λ2-0.01822)-0.01354λ2 ne2=2.3753+0.01224/(λ2-0.01667)-0.01516λ2
Refractive Indices at 1064 nm at 800 nm at 532 nm at 400 nm at 266 nm	no = 1.6545, ne = 1.5392 no = 1.6606, ne = 1.5444 no = 1.6742, ne = 1.5547 no = 1.6930, ne = 1.5679 no = 1.7585, ne = 1.6126
Thermo-optic Coefficients	dno/dT = -9.3 x 10-6/°C dne/dT = -16.6 x 10-6/°C

Nonlinear Optical Properties

Phase-matchable SH Wavelengths:	189 - 1750 nm
NLO Coefficients	d11 = 5.8 x d36(KDP) d31 = 0.05 x d11 d22 < 0.05 x d11
Effective Nonlinearity Expressions	dooe= d31 sinθ +(d11 cos3φ - d22 sin3φ) cosθ deoe= (d11 sin3φ + d22 cos3φ) cos2θ
Electro-optic Coefficients	γ11 = 2.7 pm/V, γ22, γ31 < 0.1 γ11
Half-wave Voltage	48 kV (at 1064 nm)
Damage Threshold (Bulk) at 1064nm at 532nm	5 GW/cm2 (10 ns); 10 GW/cm2 (1.3 ns) 1 GW/cm2 (10 ns); 7 GW/cm2 (250 ps)

Application Examples

BBO is of particular importance in the visible and far UV. A wide variety of phase-matching applications are possible, including the following:

Second, third, fourth and fifth harmonic generation of Nd doping lasers

Second harmonic generation to generate wavelengths as short as 204.8 nm

Shorter wavelengths (193nm) can be generated by sum frequency mixing

Frequency doubling, tripling and -mixing of Dye lasers

Second, third and fourth harmonic generation of Ti:Sapphire lasers

Optical parametric amplifier (OPA) and optical parametric oscillators (OPO)

Frequency-doubling of Argon ion, Cu-vapor and Ruby lasers

Transverse field Pockel cells made from BBO useful when high average powers or
short wavelengths used

SHG and SFG

BBO is the only NLO material which can be used to produce the fifth harmonic generation (5HG) of Nd:YAG lasers at 213 nm. Because of a small acceptance angle and large angular walkoff, good laser beam quality (small divergence, good mode condition, etc.) is the key for BBO to obtain high conversion efficiency. Tight focus of laser beam is not recommended.

NLO properties for harmonic generations with Type I PM in BBO crystal
Harmonics	SHG	THG	4HG	5HG
Effective NLO Coefficient(d36(KDP))	5.3	4.9	3.8	3.4
Acceptance Angle (mrad-cm)	1.0	0.5	0.3	0.2
Walk-off Angle (°)	3.2	4.1	4.9	5.5

BBO's OPO and OPA

The OPO and OPA of BBO are powerful tools for generating a widely tunable coherent radiation from the UV to IR. The tuning angles of type I and type II BBO OPO and OPA have been calculated, with the results shown in following, respectively.


Type I OPO Tuning Curves	Type II OPO Tuning Curves

Ultrafast Laser (Ti:sapphire)

Frequency doubling and tripling of ultrashort lasers are the applications in which BBO shows superior properties to KDP and ADP crystals. BBO crystals as thin as 0.01mm (10 µm ) for these purposes are available. A laser pulse as short as 10 fs can be efficiently frequency doubled with a thin BBO crystal in terms of both phase-velocity and group-velocity matching.